I have a linksys WRT54G router and WMP54G card. They are sitting about 5 feet away from each other. I get about 40%+ packet loss between my router and the card. While this % is fine for surfing the web, playing a game with this type of PL is very frustrating to say the least. I have no 2.4 devices.
Most of the people I talk to that notice this type of PL in there games get dropped/lagged/chopped/Two steps forward one step back. Here is a screen shot of my TCP/IP path with two graphs bottom is total route top is just between my computer and router.
http://www.starsolutionsllc.com/test/www.dslreports.jpg
Bottom line wireless is new and not even close to cable. In data Integrity and response time. To tweak your hardware and test your route I recommend
this site. The manuals/FAQs/Tutorials/Fourms are the best around for honest information about products there promises and lies.
www.dslreports.com
Hope this helps your problems.