I currently have E2160 OC @ 3.25 ghz, 4 GB DDR2 800 MHZ 4-4-4-15, 320 GB WD SATA II, and 8800 GT OC. I have so spare money from my 8800 GT OC so i could rather Step up to a 9800 GTX or get a 36 GB Raptor drive. Which will give me better benefit? Just to tell you, 36 GB Raptor would be slightly cheaper then a Step up.
The 36GB Raptor has become so obsolete, that even with 10000 RPM, you will not notice any beneficial difference between that and what you have already. If you want good hard drive performance, better than mainstream, you'll have to wait for the refresh of the raptor line to hit retail in May. Either save the money, or step up to the 9800 gtx.