BleepingComputer.com: Haveing troubles with my internet

ok hard to explain really but basically when im on my main Computer (custom built) my internet triggers on and off and my signal remains low (2 bars).
i am wireless as my dad dosnt want to run a wire to my pc.....
when im on my laptop i get full internet signal and i lose 1 bar on the odd occasion so in all its very good. i also had this problem with my older pc
but i bought a better network card on purpose thinking this was the problem. when the internet works its fast just like i want it but it will just cut out randomly
also i have a brother with lower spec network card and hes in the room opposite to me yet he gets full internet signal......

i have installed all the drivers and there maxed, changed the internet settings so they are the same as my bothers and my laptop
and really just dont know where to go from hear :/ not really much information i can give you to be honest

its just making it realy difficult to play games on .... i use to be able to play CoD MW and WoW but now when i connect i just crash out

my network card is : Tenda W322P Wireless PCI Adapter
and im not running on any proxies.

please help _Veku_ (p.s im not realy sure what information to give you so if u have any question that i might be able to answer ill gladly get back to you)