While I have my blackberry tethered to my Vaio, I can connect to the Internet and I can connect to a Small Business Server's Remote Web Workplace interface, but I can not connect to any of the servers or PCs. I'm getting the typical can't connect errors.
I can make the connection fine via wireless, but not while tethered. Does anybody have any suggestions?
I have already tried adjusting the IP header compression, Hardware Flow Control, Modem Error Control & Modem Compression; all to off.

After some reading up I fixed this myself by opening port 6100 on our firewall. Blackberry phones communicate on this port and it must be open along with 3389 and 4125 to use the Small Business Server Remote Web.
Hooray...I'm in business!