Hey guys, I've been getting random lag spikes every couple of minutes and I don't understand why.

Windows XP SP2
Intel P4 2.53 GHz
512MB PC2100 DDR RAM
ATI Radeon 9600XT 256MB DDR

Linksys Wireless network adapter Speedbooster
Linksys Wireless G Router Speedbooster

Current Console settings:

rate 15000
cl_cmdrate 75
cl_updaterate 74

Any tweak advice would be great too