From what I can tell, apparently the WG311T card, in tandem with a particular Netgear "Super-G" wireless router can achieve better throughput than the normal 802.11g standard; 108Mbps as opposed to 54Mbps. If true, that is definitely better, but I'd take that claim with a grain of salt. I have no personal experience with it, so I can't say for sure one way or the other. But if you don't have the "Super-G" router, then it doesn't matter anyway.
From the reviews on Newegg, it seems many people have had issues with the WG311, as well as the WG311T. However, I recently purchased a PSU that had many complaints, but, being persuaded by its features and a $45 MIR, I got it anyway. And it's worked for me like a charm. Granted, I haven't had it too long, but still.
So the short version: if you have the "Super-G" router, go for it and get the WG311T card. If not, there's no point in spending the extra $10.
Edit: Oh, and the PCI 2.2 thing, most likely, as long as your motherboard isn't particularly old, you've got it. If your computer came with any documentation, it's probably listed in there somewhere. If you know the motherboard's make and model, you could probably easily find the specs online, if you're worried about it. Or, if you can't find out the make/model, I could recommend a program that should let you know.