cApNhOwDy

Even if you only use your P2P when you're downloading stuff, there are still options that can make the P2P connect to the network whenever you turn on your computer, regardless of whether you're actually using the program or not.  Check and make sure that your P2P doesnt automatically connect on startup.

Okay, I have an ATI Radeon 9800 Pro, and I want to tweak it.  What the heck does that mean?  I've been reading alot about "keeping the card cool", but how am I supposed to tell how hot my video card is?  It's inside my computer, and there's no way in hell that I'm opening up my baby!!!  Is tweaking some kind of software that you use, or is it something that you do manually?

Are you using any P2P programs? (Like, Kazaa, Limewire, Morpheus?)  If so, then check and see your number of uploads.  I had a very similar problem to yours, and it turns out that my P2P program had reset it's options and let other users have access to upload from me, and i had an average of 20 users uploading from me at any given moment.  The rising and decreasing speeds may indicate a rising and slowing amount of traffic on the P2P network.

Yeah, but which one?  There's so many. 

Well, it helped me at least.  My connection has been bugging me for 5 months now.  Silly me, I had set Limewire (my fav filesharing program) to automatically resume uploads whenever I turned on my computer.  Turns out I had 50 uploads running whenever I turned on my computer.  So I cleared all of those, disabled that feature, and BAM, internet's back.  5 months of hell I lived.  Dont let your internet be slow for 5 months.