BleepingComputer.com: Please help - Upgraded my RAM and browsing got worse

I decided to upgrade the RAM in my Toshiba Satellite laptop after finally getting sick of "Low Memory" messages in Windows XP. My understanding was RAM increased the speed of your computer, so I could have Chrome open with three tabs for a while and it wouldn't start crawling my computer down to nothing. I had 256 RAM in my laptop initially. I bought a 1 GB RAM card to add. I added the card and booted up my computer. It was a lot faster bootup. I checked to see what the RAM amount was in My Computer and it was 1.whatever GB. So it was obviously in there and it was working. Sound wonderful...except when I opened chrome, my browsing was a lot slower. I went to youtube and every video I clicked on slowed my computer down to nothing and turned into a slide show immediately. I could only click on one video actually because it would lock up the browser with a slide show. This NEVER happened when I had 256 RAM in my laptop no matter what browser I used. I never got a slide show from a video. I tried Opera browser and it did the same thing. Every video was a slide show. I thought maybe I should take the 256 card out and only put the 1 GB card in. Maybe the problem is the cards aren't the same. I did that and it didn't change anything. It was still slow as a snail. It still is as I'm typing this. I have a delay on what I type. So if RAm is supposed to speed things up, why the hell did it speed up my bootup significantly, but destroy my web browsing? How can I not be able to play the same videos with 4x the RAM? Does that even make sense? Did I miss a step or something?

Some PCs can only handle so much RAM. Although, this isn't normally the symptoms of that, how old is the PC and what model is it?

It's a Toshiba Satellite A45-S121. I'm not sure how old it is.