You have to make a certain number (3) of hardware changes, any installed hardware, within 90 days. Wait 120 days between upgrades and you can go through a lot of hardware before you get nailed with the dial up registration.
I had literally replaced everything in my system until I screwed up one XMAS. I changed the DVD in and out too many times trying to get the POS to work, that along with another upgrade I did triggered Windows.
Note Stripping out hardware and reinstalling it as part of trouble shooting can cause you to exceed the change count. So before starting trouble shooting save your final hardware key file.
WOW just read that link Gonaads. Best description and utilities I've ever seen on activation. REP points time.
Ooops. Almost screwed myself. Added a stick of RAM, changed the DVD at XMAS and for some reason it thinks my video card changed??? If I pull that stick of RAM out I'll be dialing MS again. Handy little utility XPinfo.
You don't need a new Operating system. You can change everything in your PC and then activate my example indeed, recently (less than 6 months ago) I ran a Pent 4 processor, with intel mobo, with a cd rom drive, 133 ram, a different DvD burner to the one I have now, a different HD, infact I won't write the rest as to be honest over 6 months I have changed everything to new items. I was asked to activate when I finally changed to my last piece of kit the NEC DvD writer I got and I did it by phone.