wireless connectivity drops

i recently bought a gateway p-172S fx loaded with windows vista home premium that comes with Realtek RTL-8187B wireless 802.11b/g.

i had trouble keeping a constant connectivity between the laptop and the router i have set up in my house.
i notice it only happen when doing some heavy traffic over the network such as playing games, updating server list, opening web pages full of images, and so on. if i let my computer idle i can keep the connection connected.

my roouter is dlink dir-625 hardware rev A1, loaded with the latest firmware 1.09.
i tried numerous things such as using different drivers on the Realtek.
removing/try different security system wep/wap/wap2
disable ipv6
run it on wired connection (works perfect)
other wireless computer/laptop that is connected to the same router works perfectly( but they all on windows xp and macosx)

please advise
Martino