Mrfixall,
Theoretically (and I stress theoretically) the use of a crossover cable should have no effect on the performance of your chosen communication protocol. Keep in mind, however, that TCP/IP is a whole suite of protocols inter-operating at different levels...if any component at any layer is not functioning you'll have problems.
TyrantSSV makes a good point about where you should start. Once you're sure that the IP configuration of both PCs puts them within the same network, you should be able to PING each system from the other. But PINGing only verifies network connectivity...it doesn't guarantee that you'll be able to share files, etc. For network browsing and file sharing (under Windows) the NetBIOS component must be working properly. To check this, you can do the following:
Right-click Network Neighborhood and select Properties from the menu. Select TCP/IP from the component list and click the Properties button. Click the "NetBIOS" tab and make sure there is a check in the box that says "I want to enable NetBIOS over TCP/IP". Close the Network Properties sheet and get out to a DOS prompt.
From the DOS prompt, type nbtstat -s. If you see your computer name and the word "Listening" you're in good shape. If you get any kind of an error, you'll have to remove and re-install TCP/IP.
This is really only scratching the surface of TCP/IP configuration and troubleshooting. There's an awful lot to it.
Of course, now that I've gone through this whole explanation, it occurs to me to ask why you need to use TCP/IP? If you're connecting two systems directly (ie. without any connections to other networks or the Internet) why not can TCP/IP and just use NetBEUI or IPX exclusively?
Anyway, I hope you can get some use out of all this info.
Chris