really bad wireless connection

About a week and a half ago, my wireless internet connection got really weird. Anytime I play a game, it drops completely and notifies me that it has "Limited or no connectivity" or sometimes just drops completely from my home network. I am using a WMP54G v4.1. I have contacted Linksys support numerous time yet nothing has worked. I even got an RMA for a new adapter, which came today, yet 2 minutes in I could see it was no different. I changed the network, and I noticed I have better signal strength and speed when it is an open network. Obviously I can't leave it like that, so I made a different type of authentication. Same thing, it was slow and poor.

This leads me to believe that it is something with my computer. I don't know of any changes I made that would do this, so I'm at a loss. Is there any way to refresh all the internet stuff on my computer to fix this, or a setting to switch? Please help, it took about a minute to load this very page. Thanks very much in advance

Go to Control Panel->System->Hardware->Device Manager. Double click your network adapter. There should be an Advanced tab. Ensure no things such as minimum power consumption or power save mode is enabled. Set Rate to best. Roaming decision to optimize distance. Yours may be termed differently or not exist.

I looked and it is set to the most optimal settings. One thing I've noticed is I can't access the router page very well from my computer, meaning the wireless signal is weak or something. It's a slow connection to the router, which is why my internet is so slow. There must be something, but I'm lost. I guess the biggest problem is I need to get a strong connection again between the adapter and router