It will be B or G at that frequency but that's not really relevant since G is backwards compatible. Sounds like you might have WEP enabled. Remove any security layer you have. WEP, WPA, Mac addy filtering or ACL's. Start from scratch. You might considering doing a hard reset on the Router/AP to clear any settings. If your using XP i'd recommend dumping their Zero Wireless Configuration utility. It's garbase and can be disabled from your services MMC snap-in. Load/Reload the client cards drivers and install their utility and test with it. The AP should be broadcasting the SSID so you shouldn't have to worry about that and the frequency you use is only relevant if you are experiencing interference. Try playing around with the channels on the AP. If you associate after changing the channels you likely have some interference issues. There are many things to try but you gave the old "My stuff doesn't work, fix it for me" post, without giving much pertinant info. Like, what have you tried so far. What OS, Card model, AP/ROuter model, etc... Can't expect a whole lot of help with what little you have provided.
CCNA, MCSE, A+, Cisco Certified Wireless Field Engineer