This is a VB question, so you might be better asking it in a VB forum; eg,
http://www.greymatter.com/Forums/

But anyway, what does your VB code do? What, if any, data is actually tranmitted?
Forget the microcontroller for now - just put a terminal (or terminal emulator, or serial data analyser) on the port.

Don't forget: with VB, unlike an embedded micro, you do have the advangtage of all those good things like string handling, an operating system, etc, etc.

SO it's probably actually very easy to convert your number to a string & then just send it - you probably don't even have to bother with sending each character individually in turn!

BTW: Be sure to check whether your PC port setup requires any modem-control and/or flow-control lines to be set.