High Ping on CoD4!

ISP: Time-Warner Cable "Wireless Home Plan"
Adapter: Linksys Wireless-G USB Adapter (Model WUSB54GC)
OS: Windows XP Professional

Using the same set-up (computer, ISP, OS and adapter) as I am now I would see ping in the low one-hundreds at worst, other than a odd server here and there. All of a sudden my "Master Server List" ping counts read anywhere from 200 - 8,000. Once I'm in the game, assuming I don't get the "Low Ping Only" message, the pings usually lower. No higher than 300. Also, sometimes when I refresh the list, I don't get any servers or just a few. The only thing I can think of is, that since I have auto-update on, Windows went and downloaded something for me that royaly screwed me up. Do you guys know of an update that did this?

Basically, I'm looking to get my ping back where it was.

Thanks in advance to anyone who takes the time to read and/or answer this.

EDIT: Allow me to add that once I'm in the server, my ping's fairly stable and that I very rarely have any issues.