I am in the same boat; Half of the work I do is on legacy gear, and therefore requires legacy software, which only runs happily on legacy computers. Thankfully I was able to find a brand new laptop that comes with a serial port (WHAT?! - Yeah) and a virtual machine handles all my XP needs.I use several different OS. At work we use NIDA which is a Electronics training system, it is 32 bit and my newer Win 7 pc is 64 bit. The school decided a KVM switch was cheaper than buying the 64 bit software ($5k). Which means I use XP there also.
At home my everyday laptop is win 7, but, I also program 2 way radios and all my software is on a Win 2000 laptop, and a XP desktop. Most of my programming cables are for a serial port whach has gone by the wayside. Yes I have tried USB to serial adptors with a little success. Some older Motorola radios (1225) require a slow pc with a serial port, so I even have a Win 95 laptop for them.
Someone has even developed software to slow down your pc clock for Motorolas. It's called MOSLO..http://batboard.batlabs.com/viewtopic.php?f=1&t=49385
WinXP is missed, but win7 is the next best thing. I wipe my crack with Win8. I have an old laptop with Ubuntu on it, but I never use it.
One thing that's been bugging the crap out of me lately about win7 is the way that it handles metadata ("tags"). I save every service & users manual/datasheet/cheat sheet/etc that I ever download into an organized collection of PDFs. Most of these downloads have non-descriptive file names like "1336e-um001_-en-p.pdf." My collection is >10GB and in XP I was able to set my folder view to "View details" and I set up columns like "Title" and I would see the metadata ("1336 IMPACT Adjustable Frequency AC Drive") and the column "Author" and I would see "Rockwell Automation," and I could sort by (and search for) files based on this data. But in Win7 they changed up the way this metadata is handled, and now if I want to view this info I have to purchase a 3rd party "explorer" or open the file in Acrobat (not reader) and go File>properties. Apparently pictures and videos were not affected by this wonderful and all-important change.
Had he to serve the reports I have to, after every job, he will be using nothing less than me. Rest assured.I read an article somewhere that the Game of Thrones writer still uses MSDOS to write up his books.