time to replace my battery?

I've got an (old, i guess...) vaio S360. I'm under a warranty from circuitcity that has a battery replacement plan, and it's been a couple years now, so I'm wondering if my battery capacity is rather decreased by now. Running with RMClock holding my voltage to only 0.7v and with my screen brightness all the way down, I can get about 3 and a half hours. This is while browsing the internet in firefox and chatting online, so the cpu stays at 600mhz the whole time, but the wifi is on. I'm pretty sure i used to be able to get well over 4 hours, perhaps with the screen brightness not even down, but i can't really remember.

Anyone remember what kind of battery life your S360 could get when it was new with this kind of minimal activity? Or does anyone have any experience with this circuit city battery replacement plan? There is no information on when they will replace a battery on the website and the guy in the store was completely useless. (Just said "I don't know." and shoved a pamphlet at me.)

Thanks for any help!

 

It doesn't sound like your battery is showing any signs of a problem. Li-Ion battery cells degrade with time and usage.

Please refer to the battery guide for more information on the subject.

 

I don't mean to suggest that it is defective. I am aware that Lithium Ion batteries naturally lose capacity over time. My plan covers this and I was wondering how far along my battery was in its aging process, because I might stand to gain a significant amount of usage if I were to have it replaced.

I guess I should have asked, how long did people's S360s seem to last on battery power under light usage, particularly when they were newer?