i guess all i can say really is, raptors by themselves will be the fastest single hdd non scsi solution (and even raptors are about on par with 10k scsi hdds; using smaller 2.5" platters to allow for higher rpms, similar capacity platters as a result too, up until they start using PMR to increase capacity per platter, whenever that might be, consequently increasing STRs as a result too... right now its just physically not possible without PMR (or reducing the rpms), which is why you dont see larger non PMR platters on scsi hdds or raptors), but raptors are definetly more tuned for single user environments now too, i believe also... you may never see PMR on scsi based hdds though (or raptors), just wait and see i guess
the only way im suspecting youre going to see a very noticable speed increase for everyday things, using 7200rpm raid over a single raptor, is if you invest in a seperate dedicated hardware based raid controller, and theyre not cheap either (they have their own integrated logic chips for handling I/O requests, dedicated memory, and other features i believe)... superfly pointed out hes going to run his tests with an areca arc1210 pcie sata raid controller ($320 usd, which is the cheapest areca newegg has), and then compare that to onboard...
without a hardware based raid controller, going with raid 0 isnt going to offer much of a performance boost (synthetic benchmarks aside), synthetic benchmarks usually dont translate over to realworld usage very well though either... and thus without a decent controller, raid 0 has kinda limited itself to mostly just increased STRs... video audio editing, large file transfers, and faster windows boot times (due to increased, yet not intelligently managed, I/O performance)
to make a very weak (but still relative) comparison, a single raptor can be equated more to a raid 0 array of 2*7200 rpm hdds; much higher I/O transfers (smoother gameplay as a result), more heat generated, more noise when seeking, higher STRs... the downside is that your access times still take twice as long using a 7200 instead of a raptor (7-8ms raptor compared to 14-16ms 7200, due to the slower rpms), so it still takes longer to locate files, and your still unlikely chance of failure is theoretically doubled
all in all though, without a dedicated hardware raid controller, i cant see using raid 0 as being a very worthwhile thing (this coming from 4*36GB GD raptors in raid 0 with onboard software based raid myself, and i saw more of a performance boost just going with a single 74GB ADFD instead later on, for the reasons listed)... software based onboard raid 0 isnt able to intelligently organize I/O requests on its own, it relies on the cpu to do that... which is also why raid 5 performance typically sucks with onboard (cpu overhead due to managing parity)... a dedicated hardware controller handles everything like that on its own
anyhow, yeah... the smarter decision (i would believe) is just to go with a faster single hdd, and just bypass the complications of using raid 0 altogether, and you may just see more performance with a single hdd than you would see with raid 0 anyhow (unless your specific use really shows some benefit from it)... that goes against the common theme of people praising raid 0, but it is heavily based on the performance of the controller used too.
and a raptor has a 5 year warranty, which may or may not be worth it to you