Wireless keeps dropping the connection, help!

[#1]

My wireless connection keeps dropping and it's beginning to annoy me! 
I'm using a D-Link DSL-2640B modem router and a D-Link DWA-111 wireless G adapter.
I have the router plugged into a filter/into the phone line. I also have my Xbox 360 connected to my router via ethernet.

The connetion drops randomly, even when the Xbox is switched off.
Can you help?
Thanks!

[#2]

What is the signal strength and is it constant? Get netstumbler free from http://www.netstumbler.com/ and check to see if there is anyone close  you who may be interfering with you. You need to check often as people may come and go. If there is anyone close check to see if they are on the same channel as you if so change your channel.
It could be noise from some other source ie radio, TV, Microwave, fridge etc the best way to check is to get a portable small radio and tune it off any station so its quite and then walk about near the router and pc and see if it pick up any noise this may show up any device in the house giving the problem.
Note times to see if it is random or there is a pattern

[#3]

Thanks for the help! If I do need to change my channel because of another person, how would i do this? I think the problem will probably be interference from other electrical stuff tho.  Ta 

[#4]

Normally you can select the channel the wirless router uses in the wireless config section. Anything trying to connect will find the necessary channel automatically.