Don't use Vista, it never saw mine at all..
XP saw the router bueven though it flashed through it didn't actually reset to the firmware I was installing. But this was just my experiance.
I ended up using the tftp tool on an old Win98 machine, flashed it straight through first time and everything was back to normal.
One thing I did notice was that in Win98 it took ages after the flash to actually reprogram the router, had a timer screen, so maybe XP will work but just leave it for like 20 mins after it has finished so you don't interupt any install it is doing.
