I reckon a Western Digital Scorpio Blue 320GB drive would hit the spot
WD Scorpio Blue 320 GB SATA Hard Drives ( WD3200BPVT )
But one in my MacMini a while ago when I started running out of space and I'm very happy with it.
Mac
Yes, I do prefer WD to Seagate or other HDD brands - just had less probs with 'em
PS: Just realised the other parts of your question.
1) You're almost always better off with a clean install with Winblows
2) I always make 2 partitions if I am forced to use a single disk, one for the OS (whatever it may be) and apps and the other for data. With the MacMini I have an 80GB "System" partition and 240GB "Data" partition. Makes backups and migration easier.