I use the windows backup utility for this. It only copies the files (and you can select the ones to/not copy), so that right there might save a huge amount of time over a block copy*. Dunno how it might work with an OS though (I keep my apps on their own partition, and have done this sort of thing several times, it's fairly bulletproof IME). Size of the target partition is irrelevant, so long as it's big enough.
*er -- but it's a 2-step, backup+"restore" [to the new disk] process. Bonus: you have a backup copy!
Depends on whether you consider computer games "useful"...
(actually, I do also use it for photoshop).
robocopy [source] [dest] /MIR
robocopy [source] [dest] /MIR /FFT /XD "System Volume Information" /XD "$RECYCLE.BIN"