If it is not urgent to upgrade your PC, you should wait for the 65nm and Dual Core 64-bit processor based PC/Notebook, it is a great improvement to cope with Windows Vista.
Windows Vista will run on current generation PCs, but you won't get all the eye candy.
Do you think a dual core processor will improve the type of stuff you do? You must remember that in order to take advantage of the dual cores you application must be multi-threaded. If it isn't you won't see any improvement.
