Do you have a RAID card on the system that you can use to handle mirroring, or would you have to use software RAID?
How you set up the system really depends on the sort of data you are putting on it and how horrible it would be if you lost either 1) the operating system or 2) your data partition. If this is a web server, and you get nightly backups, I would mirror the 2 9gb drives and put the operating system on them. I'd also install the web site on them, assuming the site isn't really all that big, and stick the page file on the 36gb drive. If this is a web server that has a lot of streaming content or other large files, I'd put the data directory for the site on the 36gb drive. Web servers usually have a lot of static content that doesn't need to be preserved as carefully, since it can be backed up adequately every 24 hours.
If this is a database server, and you are sort of smart, but still not wanting to spend much money, I'd buy two more 36gb drives and a RAID card, and create a RAID5 array for your SQL/Oracle data and logs. And still back it up nightly. If you were really smart and had the money, I'd recommend RAID0+1 with an extra 2-drive mirror for log files.
The default page file size will probably be 1.5 gig. Set the page file min and max size both to 2 gig.
ShackDaddy