I cleared out a couple of gig of temporary files, trial installs and duplicated files (along with incremental backups - having redone a full one). And don't forget to ZIP or compress rarely used stuff.
If you really have that much, consider if it is all needed on a laptop or whether a desktop would be a better repository and laptop a portable solution.
Apologies if this is egg sucking, but if its not asked ...
anything other than your system can be sent to an exterior drive then the system itself (xp) can be sent with acronois to a dvd writer drive .the reason I do this is to reduce the system size to fit on to a dvd ..win 98 can be sent to a cd writer provided it is under the cd disk size of 700mb,and with acronis you can replace everything (must be to the same pc off course )