#1 issue when moving windows installations between machines is the IDE controller. If both machines used the same driver, you have a solid chance. If not, prepare to bash your head against the nearest wall for several hours.
If your laptop has SATA, you might be able to run cables from the laptop's internal SATA link to the desktop's old drive. Should work.
Otherwise, you'll be going from whatever your old controller was to USB mass storage. I recommend using both a helmet and some foam padding on the wall; if you live in an apartment you should do it during the day as well, as to not bother the neighbors.
SATA 1 vs SATA 2 doesn't really matter in this case. The bottleneck will be the USB link, by a very large margin. Naturally you should get SATA2 hardware as a general rule, though.