Problems with computer upgrade!

[briefcasemanx]

I installed an extra 512mb of RAM, and new 400gb hard drive, and a new DVDRW into my comp, and now whenever I start up a session in Cubase the CPU usage is WAY higher than it was before I did anything. I thought the RAM would actually helpt me use more plugins! The original 120gb hdd that has all my previous files on it now makes a slight crunching noise when playing back a project with a lot of tracks. I use an AMD 3000+ now with 1.5gig ram after the upgrade, on an asus kv8 deluxe motherboard. The new RAM I bought was cheap corsair stuff. All the ram chips installed are ddr400.

Also I restarted after installing all the stuff and i went to the BIOS and checked stuff out but didn't change anything, then I exited and it gave me some message about how I needed to put in a boot up disk. I pressed control alt delete and I think that might be what screwed everything up. Now whenever I restart it shows a quick screen that says ASUS during boot, and it never did that before.

I know it's probably hard to diagnose the exact problem but any ideas or leads would be helpful!

Thanks SLUTZ