Alternatively, Windows 7 / 8 is such a disaster that the IRS is paying a few million dollars (out of their 10 billion dollar budget) to stick with something that works.
Windows 7 (and Vista) won't run on PCs without ACPI support in the bios. I don't know how prevalent these old PCs are in the government setting but its certainly affected some POS systems for some businesses.
Ah - I meant the collective "Windows 7 & 8". Windows 7 is fine, but has already been replaced by Windows 8, so why not Windows 8? Windows 8 introduced Metro, which is hated and not really an option for the enterprise, so 8.1 has sort of removed it (but not fully). And Windows 7 support ends in 2020.
In short, it's not a confidence-inspiring roadmap, and I think waiting a year is a valid choice.
1. Size. Standard install takes up almost 20GB of hard drive space. Fresh Lubuntu, Crunchbang, or Debian takes up a gigabyte.
2. Backdoor prone black box. Something like Windows - buy licenses, get support from a 3rd party, be ignorant about product itself due to withheld software freedoms - works for the small to medium business. When you are federal scale, it makes no sense to spend tens or hundreds of millions in MS tax when you could, for a fraction of the price with a small dev team, maintain your own Linux fork. And while the IRS is on the "same side" as the NSA, who puts back doors in Windows, it should be hard to sleep at night knowing Microsoft could be bought off like that, and that China might do the same. Unless they get special source access to inspect it, at that scale they might.
3. No package management. For enterprise deployments, I've dealt with enough small businesses who just sit on half a decade old Firefox or Chrome because they can't enable the auto updater and didn't set up an Active Directory applications server. So the middle road is just having your own package repository of updates with all the machines synced to it pushing whatever new stuff you want available automatically.
And you could also throw in that a GNU/Linux distros modularity makes it much more reasonable to deploy to servers, embedded devices, and desktops at once with one maintenance crew. And if the IRS is running Windows Server.... taxpayer dollars at work, all right.
1. I used to consider the size of Windows a problem, then it occurred to me that I no longer play video games, and my video sources are all streaming. My 1TB hard drive has 800 GB free. Government employees outside of media offices and labs/shops that are heavily dependent on large data sets or large resource files like CAD or GIS data are probably not facing a data crunch on their user workstations with the current cost of hard drives.
2. Didn't like my response to this, may edit later.
3. Now this is reasonable, software installation on Windows sucks by default. However, there are some good tools out there for handling the distribution of software. I recall using some when I worked in IT at a university. Ghost had a way to do it that was essentially taking a snapshot, installing, then another snapshot. The difference was what got installed onto the rest of the computers. There was also a piece of software we used that let us handle on-demand software installation for things with limited keys (like Matlab), I don't remember (a decade ago now) what this one was. Not baked in, but it was more than serviceable as I recall.
4. IRS probably still has a fair number of mainframes. If they're like other federal agencies they'll have a mixture of Solaris, Windows and Linux servers installed depending on the contract at the time the information system was put together. Again, that modularity would be nice, but it's hardly practical unless the fed establishes one organization to be responsible for making, supporting and distributing this OS. Then you'd get a bunch of folks on the right bitching about government interfering with business, and people on both sides bitching about the security/privacy implications.
1. First, that's only a default install: you can easily package up a custom 7/8 install disc that gets down to 10-15 GBs. And if you compare that with a distro that installs a Windows-like window manager but default (say, stock Ubuntu, which takes up 5 GBs of space[1]), that gap narrows by a lot. Furthermore, it's just an irrelevant point. What's 10-20 GBs on modern desktops? Sure, the initial install will take a bit longer, but I sincerely doubt that a limiting variable for anyone right now is having a 40GB HDD instead of an 80GB HDD.
2. You are severely overestimating the ability of the government to hire a "small dev team" competent enough to build a custom Linux fork. The bulk of cost, no matter if they go Windows or Linux, is support. That's because it's really, really hard to manage software entirely through internal means, even if the product is completely open-source.
Furthermore, who's to say that the feds don't already have access to Windows source? At this point, it's impossible to know, but the idea that MS could be "bought off" by China is absurd. They're an American company whose operations and finances are largely based in the United States. You would have to have a high-ranking executive (or collection of executives) commit blatant treason, high the bribery money in some other country, AND convince a large number of MS developers to be completely quiet about an exploit placed in Windows source code on purpose. And not an exploit placed there under the threat of criminal punishment by the "legitimate" American government but an exploit that would send hundreds of employees to federal prison. I'm paranoid enough to admit that it is theoretically possible, but waaaaaay less likely than waaaaaaay more things that we should be legitimately worried about.
3. You say there's "no package management" and then you go on to explain how there is package management but that it's not setup correctly. The IRS is not a small business. Microsoft provides high-end support to them so that they can properly setup Active Directory and WSUS. And if they went Debian or Ubuntu, they'd pay the same money to properly setup those package managers.
Not to mention all the sheer costs of deploying and transitioning to a completely new infrastructure, as well as training thousands of relatively low-skill workers to use a completely foreign system. Oh, and rebuilding tons of custom software that wouldn't be in any public package repository anyway.
Anyway, OP's original point was that Windows 7 and 8 are garbage compared to XP, which is blatantly wrong. They're both very stable operating systems, and while it's fine to debate WHEN MS should cut off support for XP, it's an inevitable fact that they eventually MUST. The IRS has to upgrade eventually, and they've had a heads up for a while. It should've been done already.
To me, that seems like a very prudent decision.