i'm getting a replacement computer because mine's been such a hassle. woohoo! anyhow, i just have the base 2.2 ghz (120 gb, 128 vid) model now, but they asked if i'd be interested in upgrading. is it worth $500 to go the next step up? (2.4 ghz, 160 GB, 256 vid) i do graphic and web design, so the extra storage and processor speed are tempting. is it really worth it though?