Powerbook G4 15" RIDICULOUSLY slow internet. Have I tried everything?

Okay, I've had this USED laptop since last August, and up until last month the internet was super awesome and fast and lovely. Then, I'm ALMOST POSITIVE, the last update was like some big Adobe THING, and it seemed like soon after that my Airport connection was very low (like 1 or 2 out of 4 bars are full) in comparison to before, and my internet REFUSED to load anything.

After googling around, I have:
-Updated the firmware on my wireless router (Linksys wrt54gs)
-Gone into my network settings and changed my dns servers to the OpenDNS.com ones, and also to the 4.2.2.1 and 4.2.2.2 ones.
-completely restarted my router
-changed the password on my router just in case someone was stealing my wireless connection?

none of these things have made ANY change.
I have to click the reload button about 50 times, (no joke) in order for a page to at least HALFWAY load, and it's just ridiculous.

anyway, I'm not sure what is wrong or if i need a new router, but my desktop PC works fine (internet-wise) and my brother has a Gateway laptop that is running Windows XP that he also says suddenly got slow internet performance right around the time mine did.

i'm running OSX tiger 10.4.2 (heh, i'm pretty sure)

okay, well cool, this is something new.

i will try this even though i don't really know what i'm doing.

haha, it's downloading right now, it's going to take a while because my connections sucks.

but thank you very much. we'll see if this works.

ooooookay, well

whatever that did,

it DID NOT fix my slow internet.

at all.

thank you, but does anyone else have any suggestions as to how i can fix this problem, or should i just buy a new router?