1. Go to storagereview.com and browse around.
2. Go a site such as hypermicro.com and browse the selection adn bowse for drives and go back to storage review for their performance stats.
Inititially I would say get any 15K(such as an IBM 36z15) as your system drive.
For your storage drive I would recommend at least a 36GB drive to cover any overhead.
Maxtor is another very good choice for yo8ur storage(10krpm) drive. Other drives which you might want to look into are Fujitsu's line as they have proved to be excellent in the server maket and I'm sure there quality will serve you well.
A nice combo
OS DRIVE: IBM Ultrastar "Piranha" 36Z15 18.4GB 15000rpm $ 129 from hypermicro.com
STORAGE DRIVE:Fujitsu MAM 36GB 15,000rpm $280 from NEwegg.com:
For $409 plus S/H you get 2 (count them again if you want

) 15,000rpm drives and you get the performance and quality of both IBM and Fujitsu.
Enjoy.