If you bought it retail, the box should DEFINITELY state whether its an ultra our not. The big deal is whether you bought an Ultra rev 1 or Ultra revison 2. You can only tell by th the specs of the Memory and the GPU core clock frequency. I don't remember the exact specs on the FreForce FX 5600 Ultra revisonn 2, I think 400/400. I'll go check though. Also, it doesn't matter which FX card you bought because they are all total crap at DX9 performance. I highly reccomend you send that FX booard and get a Radeon 9600 Pro for cheaper. It will also be much faster in DX9 games. I'll post the link to the benchmarks pretty soon, if I don't forget.
My OS features preemptive multitasking, a fully interactive command line, & support for 640K of RAM!