Kind of depends on your eventual goals.
If you want to write small, usefull little things to help automate your work in Windows, I recommend Visual Basic. It's not real fast, but it's built into nearly everything Microsoft makes.
If you want to create web pages, learn HTML, Java, PHP, etc. (VBScript if you stick with Microsoft)
If you want to develop commercial software, you'll really need to invest in learning C++ or at least Delphi, IMO.
That's my $0.02 worth.