Well ... I'll warn you, it's pretty propellerheaded stuff. Interesting though, if you like that sort of thing. I'm an old prophead from the days when floppy disks were actually floppy.
The Yahoo API is very useful. This link gives a breakdown of how it works:
However, interrogating Yahoo (or Google) for one stock at a time is very slow, and having to update the alphabet soup for a multiple call is a pain. Excel is easier to work with TBH, but OpenOffice is free and I'm a cheapskate...
So I use a much Heath Robinsoned version of the stuff you can find here:
Wish I could be of more help, but without knowing whether you're comfortable managing macro libraries and all that jazz, I can't really give you a one-stop solution. Sorry.