@Joe, there's nothing wrong with that. If one has a lot of cash tied up in perfectly working equipment that was built to use with XP, then by all means, run it. I have a friend who has everything in his home XP based, including his media center, which he has a lot of money in. BTW, that was a killer deal on Windows 7 in the summer of '09, I got that email also. Up to 25 copies for $49.99. Many of those copies were resold through online auctions, once 7 was released.
He bought his daughter a new Windows 7 notebook for Christmas (2009), had all kinds of trouble getting it to work with the network printer. I really didn't know what to tell him, except to join a forum & create a thread about it. He did, and he was told to "get in tune with the times" & upgrade everything to Win 7. Damn, it (Win 7) had only been released for 2 months.
My friend went on a rant over that, said that he wasn't going to replace over $4,000 in perfectly fine working equipment just to connect a printer to a new laptop. He bought a copy of XP Pro from Newegg (it was still available there at the time), and created a dual boot for her. Everyone was happy.
I still use XP, especially the Media Center Edition, watched the recent Super Bowl on it, runs fine on my PC. As far as my external accessories goes, everything works with XP & Win 7. One printer even works with Windows 2000. It took a Vista 64 bit driver to make it (a Dell 720 Photo Printer) to make it work with Windows 7 64 bit. Many products made for Vista works quite well with Windows 7, and will probably work with Windows 8.
The way I see it is, everyone is different, and so is their situation. Most any modern OS, including XP, is still quite adequate, it's still in many doctors offices, hospitals, & many other businesses. Last year, I had to go for a heart exam, an echo (sort of an ultrasound procedure) was done. When I was turned over to where I was facing the PC that he was using, I noticed that it was XP, by the Start Menu icon. 2 full years after 7 was released, in a very modern facility. So it's not like XP is dead, although MS would probably like it to be.
Run it till the wheels fall off, if you must.
Cat