The PS3 has a completely different architecture to the PC.
CPU
CELL B.E can achieve a whooping 200GFLOPS while your Quad core cpu can achieve about 60-70GFLOPS, bare in mind that the coding must be optimized to achieve this.
The 7 SPE are actually vectorized processors that can help the RSX in gfx calculations most notable Vertex, the PPE which is actually the same as the tri-core CPU on X360 is a general purpose CPU,it is Super-Scalar, like a normal Pentium 4(with a little difference because it is actually Power-PC).
To know more about the CELL Broadband Engine check the
official Sony release.
GPU
The RSX is like any other GPU and it is based on G70(Geforce 7800) with 136 shader operations per clock. It also contains 24 pixel and 8 vertex independent pipelines, so basically it is limited to this number while the X360 can use up to 48 pipelines for either vertex or shader. No info regarding Floating point performance but lets just stick to the slides by Nvidia during E3 that it can do 1.8 TFLOPS(?).
The main difference from the PC is that the RSX has access to CELLs RAM XDR(i know it is present in PCs as Turbo Cache) but XDR is a high performance RAM that is used in high end GPUs, the interface that links them is called FlexIO. To make things easier you can say that XDR is between DDR3 and GDDR4.
You cant actually compare the PS3 to the PC because the PC has hardware that you can actually configure to suit your taste but of course on the PS3 you cant, thats what puts the PC at an advantage because if you can afford a high end PC that can run games at 1080p and in 3D then of course it is clear that the PC wins. But if you have an old PC that is like 4 years old then of course the PS3 will run the games better.
In theory or you can say in a highly optimized scenario for the PS3 you can use the Blu-ray to have uncompressed textures in it at 720p (so less stress on the GPU) and CELL helping in vertex shaders as well as using every SPE for something like AI, video, logic, sound....etc. Achieving all this will lead to games such as Uncharted 2 and God of War III.
EDIT: Welcome to the Forums.