Thinking of things in bits doesn't really work any more, particularly since manufacturers had the tendency to choose whatever metric had the highest bits, such as the memory to CPU bus.
You're better off comparing the CPUs and graphics card and ignoring whatever bits they claim.
The PS3 has a 3.2GHz Cell processor. The Cell processor is a 9-CPU setup which has one central processor (called a PPE, based on the IBM PowerPC 970) and 8 math units (called SPEs), although software is only allowed to use 7 of them. The system has 256MB system RAM and 256MB video RAM. It has a custom nVidia graphics processor known as the RSX 'Reality Synthesizer', similar to nVidia's N47 (GeForce 7800) GPU running at 550Mhz.
The Xbox 360 has a Xenon processor, which is a tri-core 3.2GHz IBM PowerPC processor based on the central processor of the Cell system the PS3 uses. This may seem strange, since the Xbox 360 came out a year before the PS3, but the processor was in development for years before that. The system has 512MB system RAM, which is shared with the graphics processor. It has a custom ATI graphics processor known as the Xenos, which is similar to the R520 (Radeon X1900 series) GPU running at 500Mhz. The newer S units combine the CPU and GPU into a single chip (more or less).
The Wii uses a Broadway CPU, developed by IBM and based on their PowerPC platform (are you seeing a pattern here?). The exact specifications are not known, but is believed to be a 729Mhz system. The system has 64MB system RAM and 24MB video RAM. It is paired with the ATI Hollywood graphics processor, believed to run at 243Mhz.
The Xbox 360 and PS3 CPUs aren't too bad compared to today's CPUs speed wise. The Wii's processor was dated even when it came out.
The graphics cards are far more dated than the CPUs. nVidia has released 5 new GPU generations since then, some of which had several sub-generations in it. ATI has released 4 new GPU generations since then, some of which had several sub-generations in it. DirectX has moved forward 2 generations and introduced new features, including updated Shader models. Video RAM has also increased, with modern cards shipping upwards of 1GB RAM just for video, and computer systems in general hitting the 4GB and 8GB marks.