This might be worth looking at by the toms hardware folks (unless its been done before or someone knows offhand) but I was curious if it were better to do a single SSD vs 2 Western Digital RE4 WD1503FYYS 1.5TB 7200 RPM 64MB (raid 0)
A SSD will be much faster than a mechanical drive, including a small RAID 0. Mechanical drives have a higher latency because they have to wait for the data to spin beneath the read heads. There are no moving parts in a SSD.
I'd like to see more data on this myself. It seems to me that access times will be much faster on the SSD (in part due to latency, as described above), but throughput could go either way, with Writes in particular likely to favor the RAID. Does anyone have links to some benchmarks? I'm at work right now and there are limits to what I can search and/or access.
TRIM isn't important for Sandforce based drives. They have built in garbage collection which effectively achieves the same thing. i.e. You can safely RAID 0 Sandforce drives and not lose any performance over time.
One additional point, OP. RAID 0 setups are a lot more likely to fail than single-drive setups, and especially more likely to fail in a way that will leave your data unrecoverable. Clonezilla doesn't work with failed RAID 0 sets.
So if you do RAID 0, backup early and backup often. And no, RAID 1 is not a substitute for backups.