Size of vista partitions?

I asked this in new builds, as I am going to be building a single drive 640GB WD Black Caviar system, and am wondering how I should partition my drives. However, I am having some trouble getting some of my Vista specific questions answered, so I figured I would post a question here as well.

I understand that partitioning is not a real performance booster, but I like to do it to keep drives organized and defragmented better.

My question is how large does a Vista partition need to be? I did this for my XP machine and had 20GB set aside for my C: drive there.

I am also wondering where I should put my page file. Should it be on the system partition (C), or a different one, like the next partition.

Finally, will I notice any performance hits for partitioning into 4-5 separate volumes?

Thank you for the link. I have planned to put about 30gigs aside for the C: drive, just in case for some of the little things that end up throwing themselves onto that drive. I will then create a 10 gig partition specifically for a system page file, then pretty much split the last section into data/docus and games/programs.

This will prevent any page file corruption, and with 4 gigs of ram, it should hopefully not be writing too much into the page file anyway.

Thanks for the advice!