Installed Linksys wireless card in PC--good signal, slow internet

I just installed a Linksys wireless card into my PC a few days ago. The installation went smoothly, but I'm not getting a very good conection to the internet. Sometimes the internet will run pretty fast, but most of the time it's slower than what a direct cable connection would be. Especially in games I notice this (quite a bit of lag), and while downloading more than one thing/uploading stuff.

The computer upstairs where the access point is (connected directly to our Comcast connection) runs fine and fast.

Can anyone tell me why my connection is so slow?

Thanks.

because wireless is slow

wired > wireless

Cordless phones
Microwaves
other wireless equipment

Those are all things that can interfere with wireless connections. All that crap they throw out about 112 Mbps with "Xtreme Wireless G" is in laboratory conditions, with proper line-of-sight and no obstacles.

Wireless is for internet surfing, not playing games. It is a general mass-market thing. Run some cat5e and use at least 100baseT. Wired network equipment is cheap.

All that said, you can mitigate wireless problems by trying another channel, by making sure your wireless router has encryption enabled and thus your neighbor isn't leeching to download p2p stuff, by getting a better router and/or a higher gain antenna, and by locating the antennas/router away from the wall, away from microwaves and cordless phones.