I was curious if its better to have 2 hard drives in one system. Load all system files on one and the other all games?
Can you mix the makers? 1 Seagate, 1 WD
Can you mix types: 1 Sata 1.5Gb/s
1 Sata 3GB/s
* raptor is too high at the moment *
In general you will be better off with two hard drives.
The idea with two hard drives is to balance the I/O load across the drives.
One simple optimization is to have the O/S on one drive and its swapfile on the other drive. Partition your drives wisely so the load is balanced and backups are easy.
There is an older thread titled "why two hard drives" (if I recall correctly) that gives partitioning suggestions with two hard drives.
In general, you can mix and match drives without any ill effects. As the poster above said, if you intend to RAID your drives, it is better to do so with identical drives (though this is not required but it prevents some minor problems).
HTH.