i will write here some facts:

1) about POWER of RSX:

RSX
5 shader ALU operations per pipeline per cycle (2 vector4 and 2 scalar (dual/co-issue) and fog ALU)
27 FLOPS per pipeline per cycle
68 billion shader operations per second theoretical maximum ( ((5 ALU x 24 pixel pipelines) + (2 ALU x 8 vetrex pipelines)) x 500 MHz )
364 GFLOPS ( ((27 FLOPS x 24 pixel pipelines) + (10 FLOPS x 8 vertex pipelines)) x 500 MHz )
24 filtered and 32 unfiltered texture samples per clock
Maximum polygon count: 333.3 million polygons per second (in HS RSX _alone_ 3MT = 90MT/s)

Xenos
2 shader ALU operations per pipeline per cycle (1 vector4 and 1 scalar, co-issued)
10 FLOPS per pipeline per cycle
48 billion shader operations per second theoretical maximum (2 ALU x 48 shader pipelines x 500 MHz)
240 GFLOPS (10 FLOPS x 48 shader pipelines x 500 MHz)
16 filtered and 16 unfiltered texture samples per clock
Maximum polygon count: 500 million triangles per second (in DR _with cpu_ only 4MT per frame with 30fps = ~120MT/s, 4 times less)
http://forum.beyond3d.com/showthread.php?t=31532&page=3

2) Aand about RSX and Cell:

[...]

Regarding cpu, yes its totally different arguments. The 360's is a very standard setup, a bunch of cores that can all see main memory. The advantage to this is that lots of thread coded written over the years can be ported to it easily. For example, Valve (the Half Life guys) are writing an entirely threaded engine for the PC. When it's done, porting it to the 360 will be easy. How about porting it to the PS3? Nope, won't work, it's a totally different setup. The PS3's main core is basically the same, but its spu's can't see main memory. Each one has 256k that it can work with, so you need to rewrite your code to pack things into 256k chunks, feed it to the spu's to process it, then copy it all back to main memory. In other words, you've gotta rewrite your code.

Now before I get jumped on here let me briefly mention the downsides. The 360's cpu setup is painfully easy to code for. But, they really aren't all that fast. Worse yet, all three cores use the same memory controller so the three cores are not three times the power of the one core on the PS3 due to some overhead. The PS3's spu's on the other hand are monstrously fast. You need to setup your data correctly to work with them, but once thats done then yes, the 360's cpu setup is crap compared to fully working spu's. I say fully working because most current games out there barely even touch on them, it will take time to re-write everything. I haven't done spu coding....yet. I will be though in 2007 which will be pretty cool.