I think it's the Oracle docs that say swap should be twice RAM or 400MB. I personally budget swap for 2-3 times RAM and never less than 1 gigabyte (especially because disk space is so cheap nowadays) even if I'm not running Oracle. I'm currently running 384 MB RAM with 1 gig of swap (no Oracle) on a 9.1GB drive (puny, but fast, since it's a 10,000rpm Ultra160 drive). You can create swapfiles, but it's better to use a raw swap partition (or even another disk).
If you're going to deal with security, you should have a section on performance tuning (or at least specify when you are doing something for security reasons, performance reasons, or both).
More RAM, more disk spindles (nothing but SCSI for me). I always keep user accounts (home directories), web software, third party apps (databases, etc.) off the root drive. I guess one topic you might consider is mirroring the root drive (I don't do it myself). I prefer ECC memory myself, but my current motherboard (ASUS CUSL2 w/Intel i815E chipset) doesn't enable ECC (ECC DIMMS work though).
