Can my setup on the mboard or Windows XP be effecting my speed??

I'm getting a cruddy 300-400 Kb/s for download speeds. I've tried with and without a router.

I did notice that my laptop (Windows 2000) gets a little better download speed (around 400-500) but still pretty bad.

I tried to play RtCW and the servers tell me my ping is too high (doh!) ... I have Comcast cable.

I did build a box and complete it late last week. However, the problem seemed to occur a few days after it was complete.

Windows XP Pro
Athalon 1800+
Epox 8KHa+
512 PC2100 DDR RAM
Linksys 10/1000 bit Lan
ATA 66 Hard Drive
Hercules Geforce 2 Pro 64 Meg DDR Video

If I missed any info you need let me know!