I have big problem recently i started to play tourneys and when its about to be my round there is a massive lagg and i get disconnected

here is my conf: Windows xp Proffesional
ati radeon X1950 pro
intel i3-2100 3.10 ghz
2x kingston ddr III SDRAM 4096 MBytes
256 KBytes internet

i tryed lowering the graphics it didn't work