What I'd recommend doing is loading your OS onto that 10 GB drive and using the new 80 for installs/files/games/whaever else (cough pr0n).
The page file is just what your system uses for backup RAM when your performing system intense tasks. This uses a chunk of your HD to simulate ram by writing and reading from it. At most you'd need a Gig for your Page file, but I believe deafult is around 750MB and windows changes the size based upon usage. 10GB would just be overkill.