Ok, what I think you want to do is:
Defrag your hard drive, so your current data doesnt have odd pieces scattered in areas we're going to erase.
Use something to resize your current windows partition to just hold the data it currently has on it. Partition Magic is often mentioned.
Try installing again, but this time not selecting so many packages, or maybe setting the new partition sizes yourself in the config.
I'm a newbie but I dont think you should be pushing 3-5 gigs unless you installed every window manager and all other packages etc.
I'm no where near sure of this, but I think I've made a few of the right noises and pushed you in the correct direction.
Or do what I did, get a second harddrive, then have two working OSs on one pc (providing you dont screw up the Master Boot Record like me too