Its not really THAT powerful, but then again it can't be compared directly to the x86 machines that Anand's servers use since they're totally different ISA's and run different applications. Based on spec scores however, its neck to neck with current high end x86 machines in integer scores, but much better in floating point, which have always been the hallmarks of RISC based machines without the kludge of the x86 floating point stack, but a flat register file model.
The difference is in reliability. SUN workstations/servers are arguably the most reliable and stable in the world, not only compared to x86 machines, but to other manufacturers as well(HP, Alpha, SGI, IBM, etc). Also, many applications are optimized, or at least support SUN more, as its the defacto platform for many applications. They are, after all, the "dot in dotcom"
That being said, you probably won't be able to play Q3 on it at all despite there being a Solaris Quake3 port. Their graphics performance is sorely lacking. I think their top of the line graphics cards are the Elite M6, which are dual board Elite M3s. These go way back at least 4 years ago(I remember reading about them and drooling over their power back in 96 when the V2 wasn't even out).