WRT54GS problems with Xbox 360

I've had a Linksys WRT54GS router with Speedboost for a year now. My dad is somewhat of a networking expert and he set the whole thing up. Everything worked perfected for about 4-5 months. But, something happened back around March and I've had little quirky things occur that I cannot seem to fix (note - they all involve my Xbox 360):

- the connection to my Xbox 360 drops everytime I surf from my hardwired desktop (it doesn't drop when I surf from my laptop). No other wireless devices drop when I surf from my desktop besides my Xbox 360.

- about 70% of the time I turn off my Xbox 360 it doesn't connect with the router the next time I turn it on. I have to power down both the modem and router before it will reconnect.

- all this happens when it is hardwired as well

I use a protected WEP network. I've had my dad come over the last couple of weekends to try and fix it. We've reset the modem and made adjustments to the router (like opening four ports that 1-800-4MYXBOX told us to open). We've downloaded the latest software revisions from Linksys - I think we downloaded version 5. All this has been to no avail. I am at my wits end and am ready to just completely ditch this router and buy a new one.

Are there any other suggestions anyone can make to try and help remedy this situation? I have never been so frustrated.