Internet is painfully slow, across any app.

Hi everyone --

I've searched all of the forum topics I could find related to this, and none of the discussed solutions have helped me.

My internet is brutally slow, regardless of the app, including Safari, App Store, Skype, etc.

Another computer in the household has Windows and is running fine.

I have tried all of the reasonable attempts to fix this that I've read about, including:

Punching in new DNS codes in the Network area of System Preferences.

Deleted the cache, the browser history in Safari, and disabling browser plug ins.

I've uninstalled and reinstalled Flash player (as this is where the connection suffers the most, in trying to stream videos on BBC, YouTube, etc).

Going into my Library then moving and deleting the ".plist" for Safari.

In general, on websites or the App Store for example, what happens is -- basic text will pop up after about 3 or 4 seconds of hanging, then even the slightest bit of content, including thumbnails, take several seconds per image. Anything even slightly more intense on bandwidth, like a streaming video or Flash menu, takes forever to load, if not outright gives up on me and never loads.

My machine is on Snow Leopard, a white Macbook, OSX is currently 10.6.8, which I believe I've had for several months, but this problem is only a day or two old. If I recall correctly, I did install the latest Security Update -- whatever the new ones are circa Feb. 3rd, 2012 -- within a day or two BEFORE this problem started happening... I believe this may be the culprit but strange in that there was some time before this problem surfaced, or so it seemed.

Does anybody know what more I could do?

Thanks!