remote control for my computer

Both of those are RF not IR but Girder should be able to handle the MR26A serial output.

If both of those devices are RF does that mean they are probably compatible with each other? Also, how complicated are the codes or whatever you want to call it that are transmitted by RF? I would like to write a program in Visual Basic that could take the input from the serial port to execute different macros.

Yes, they are compatible.

The MR26A outputs a 2 byte header, 2 data bytes and a 1 byte footer. The details are given here...

In hexadecimal, it's always .

One thing I missed was that you want "programmable" buttons on the remote. The KR22A allows you to assign an X-10 address (from a set of 256) to the first set of buttons. The next 3 sets automatically follow in sequence and the last set (Dim/Bright) send codes that depend on which address was assined to the first pair. While I suspect it will do what you want, the button "progammability" is extremely limited.

ftp://ftp.x10.com/pub/manuals/kr22a-is.pdf