Just got a new Rev C iMac. It came with 512MB RAM standard. I'm going to upgrade it, but should I put in one gig or two? One gig can be had for as little as $80, but if I ever want more I'll have to toss that one (there's only one slot). So should I just bite the bullet and go for 2 gigs? It'll run me about $230. I don't do any really heavy lifting with my iMac...the most I do is basic video editing in iMovie, photo editing in Photoshop Elements, and DVD burning in iDVD or Toast. What do you guys think?