Quite easy:
Get Visual Studio Pro 2010 (Trial if you must)
Get Cuda SDK 5.5
Get the source code from github (google cudaminer)
Exctract source code in it's own folder
Get libraries from first post by Christian (almost 50mb)
Extract libraries to the same folder that the source code folder is in, so not to the source code folder but one up.
Open the .sln file in the source code with Visual Studio.
Select which version you want to compile, and compile it.
If it errors:
Go to your Microsoft Visual Studio 10.0\VC\bin folder and rename or relocate cvtres.exe and do the same with another cvtres.exe under Microsoft Visual Studio 10.0\VC\bin\amd64, then run Visual Studio 2010 and try compiling.
If it doesn't work, just change everything back.
There are many versions of CUDA SDK on the page. If I want to compile on 64 bit Windows 7 to run on 32 bit Windows XP and 64 bit Windows 7, which version should I download?
The WinXP PC only has 1GB system RAM. Is that OK?
Thanks.