Get disconnect notice when playing online games usaully around 8-9pm. Why???

Hi all, first my system specs:

LOCATION: Upstate N.Y.
Road Runner internet connection (recently replaced the cable modem).

Linksys wireless router model # WRT54G (my gaming machine is connected with CAT. 5 line though, not wireless, And my wife used the wireless connection,with proper security in play of course).

COMPUTER SYSTEM:
Athlon 2600 cpu
1 gig memory
geforce 6800 video w/128mb
60 gig hd
using sound blaster ct4740 card (will be upgrading to audigy 2)

PROBLEM: There are several different games I play (most are first person shooter).
1. Mohaa Breakthrough
2. COD2
3. F.E.A.R. Combat
4. Neverwinter Nights Diamond edition
5. Almost always online with friends on teamspeak when playing there games.

I can usually play awhile before any problems arise, then bam, I get a slow server notice. Then one of two things will happen: I'll either get killed then I can respawn like nothing happened, or I'll get disconnected. I'll also get disconnected from teamspeak (I have the automatic reconnect box checked, so I do get reconnected on that). It can happen during the day when I play, and usually seems to happen around 8 to 9 pm at night. What can I do and/or how do I investigate the problem.