I recently bought a 2008 iMac (2.4Ghz Intel Core 2 Duo, 4GB RAM, ATI Radeon HD 2400 XT 128 MB) and have found it sluggish. Whenever I try watching video using VLC it stutters. I was using an older 2006 MacBook Pro (2.16Ghz Intel Core 2 Duo, 3GB RAM) which felt quicker. I suspect the internal HDD (which has never been replaced) is the problem but I'm only going by gut feeling. Should I just go ahead and order a new drive? I'm looking in activity monitor and everything looks fine. I'm only running basic applications like Firefox, iCal, and VLC. When I verify disk permissions in disk utility it comes up with a few errors, and when I try to repair those errors they just reappear again. Any suggestions? I know it's an old machine, but all I need it for is web browsing, video playback, iTunes, etc. Surely it should run better than my old MacBook Pro. Also, I have done a clean install of Lion.