Expecting the OEMs of three (presumably obsolete XP) printers to provide the latest drivers for an OS that is two generations ahead of XP is NAÏVE at best. You did clarify that your need to rebuild a Windows 7 system was due to a virus and NOT inherent system degradation over time.
(BTW, how did an IT professional such as yourself let a virus in, anyway?) I have encounter viruses on a handful of Web pages under Windows 7 but I haven't had to rebuild a system due to a virus since before Windows 2000! My AV software has always protected me.
I have been running Windows 7 since RC hit the streets and have seen no system degradation of any kind.
The examples you provide are not common in IT shops who maintain realistic hardware lifecycles (three to five years). Moving beyond five years (or worse -- waiting until something breaks) to replace hardware means you have no money budgeted to fix things when they break. It means that you have no money budgeted to migrate to new hardware or software when you need to. Microsoft announced the 'End of Support' for Windows XP in 2007, when Windows Vista Shipped. They later extended that 'End-of-Support' from 2011 to 2014.
No one running Windows XP today has a legitimate excuse for not making plans to migrate to Windows 7 long before now. In the long run, those folks who keep stalling until an upgrade is no longer a choice -- but instead an absolute necessity, will spend more money and more time to migrate to Windows 7 later than they could possibly spend by having done their homework over the last five year.
It's like the grasshopper and the ants.
I use Win7 at home, and I run an XP shop at work. Pros: Windows search is built-in to the start menu, making it almost like a command line...sort of. Cons: Windows search is slow, and doesn't find things all that well. Aero is terrible -- why does anyone need it? User Account Control is awful -- slow, cumbersome and confusing. And it's amazing how BROKEN Windows Explorer is now, both from a visual standpoint (nearly invisible column separators) and a usability standpoint (left nav moves non-intuitively, deleting folders often gives 'in use' messages). And Microsoft even screwed up 'My Documents' even more! And Libraries? The more it tries to make it easier, the more confusing and non-intuitive it makes it. More and more people are saying, 'Gee, my iPhone works great, and is so intuitive, easy-to-use, and trouble-free... Maybe I should switch to Apple for my computer, too!'
I'm the IT admin at a small company with 85 clients at three locations, plus some outbound sales people. We started the migration to Win 7 about a year ago and haven't looked back. We have less than 10 XP systems left, which will be retired shortly. The Win 7 experience has been a bit challenging because of 1) unsupported printers and other devices that we had to replace; and 2) apps that wouldn't work in Win 7 at all, or that require lots of coaxing. All in all, the Win 7 experience has been very positive for the users and IT. Systems are reliable, stable and more secure than ever. (The biggest outcry from users has been the move from Office 2003 to 2007/2010, because of the drastic change in user interface).
I can understand the hesitance for companies deeply entrenched in XP to change, especially if XP 'ain't broken.' But the problem with that kind of backwards thinking is that it grows day by day, as does XP's obsolescence. The best way to get IT moving? Take away its XP systems, give it shiny, new Win 7 boxes, and let it figure it out. Seriously, in a week it'll be in love with 7 and looking forward to the day it unplugs the last XP box. At least that's my experience. Yes, some apps will be especially challenging. This is nothing new. From someone who's been at this for the move from DOS to Windows, it's just life in the IT world. You know you're going to do it sooner or later. Do it sooner and benefit from it.
Win 7 aside, in the data center we started moving from Windows Server 2003 to 2008 R2. Also a nice improvement, but the change from x86 to x64 is a chore. By far, the most difficult project of all was the move from Exchange Server 2003 to 2010. Now that it's done, it's running beautifully.
As the lone IT guy at my company, it can be frustrating and daunting to keep up with the constant change in technology. But I can say once we completed, the experience is mostly positive all around.