Maintenance was probably the wrong word to use for what I was describing, that was a bad on my part. I basically partition my drives like that so I can Windows on a seperate partition, my other applications on a seperate partition, and my primary files on another partition. I use a 4th partition for dealing with programs and stuff I'm not sure about, that way if anything goes wrong, I can format that partition and my others are left untouched. The same goes with my other partitions.
Anyways, if you're looking to save space and actually carry out some "maintenence", there's a bunch of things you can do. Regular defragmenting and error checking is crucial, and regular archives are also a good idea. Two big things I can think off right away which will save you some space include System Restore and Hybernation. Disable these and you will notice a great amount of disk space regained.
Intel C2D E6320 / AMD Athlon X2 3800+
Gigabyte 965P DS3 / DFI nF4 Ultra-D
2GB OCZ Gold PC2-6400 / 2GB OCZ Gold PC4000
eVGA 8800GTS 320MB / eVGA 6800GS 256MB
150GB Raptor / 74GB Raptor
2x500GB / 320GB
OCZ GameXStreme 850w / OCZ StealthXStream 600w