extremely slow macbook - memory?

Hi! So I got my Macbook in November 2007. I couldn't be happier. But... it has become EXTREMELY slow. When typing, it will often "delay" and take a couple minutes for the type to show up. It takes minutes for programs to open and often times my Safari will freeze temporarily when trying to switch between tabs. I think I have the rotating multi-colored circle more than an actual arrow. Now, I have no idea what could be causing this but I am thinking maybe the memory?

I have iStat and my memory section reads as follows...

Wired: 299MB
Active: 385MB
Inactive: 148MB
Free: 187MB (has been as low as 17!)

Would this have anything to do with it? If not... has anyone else experienced this problem? I have AppleCare and am considering taking it in at the end of the school semester to see what sort of "diagnostics" test they can run.

But if anyone has any experience with this I would appreciate any help!

You didn't show the specs for your machine but it appears it only has 1 GB of memory? Also, how much space remains on your hard drive?

Regards.

Sorry... yeah I'm assuming that's how much memory. It was the Macbook that was $999 so it's not decked out by any means.

I have approximately 40GB remaining on my hard drive.

How many things are you running at a time, particularly when typing lags?

I never have more than a few programs open at a time... I like to keep them all closed. Usually it's Safari (no more than 5 tabs usually), maybe Word, and Preview is running but not open.

Nothing too much...

Have you done system updates recently? Those can harm or help sometimes...
my iBook was getting astoundingly laggy... so one day I did my system updates after months of having not, and it sped up about 4x.

i do the software updates regularly... are these the same as system updates?

Yes sorry that's what I meant. Did the slowing start right after a software update?

I can't be sure... it's been going on for a couple months. The ONLY thing I can think of was that I installed an anti-virus software (for some reason I got super paranoid) and it seemed after that it really slowed down. I've since deleted the program but it hasn't improved the speed.

Hm...

is it still under warranty?

Yep. I just got AppleCare for Christmas so I'm good for another two years. I can't take it in until the end of the semester (college) but if it persists... I'm going to see what the folks at the Genius Bar can do.