Advice on new system

[PG44]

I think the time has come to update the old laptop, but I am looking for some direction on what will best meet my needs. We will basically use it for internet, photo editing, SD camcorder video editing and other light apps.

I am looking at the Toshiba P300 laptop as an option, because it has dedicated video memory and firewire (required for the camcorder input), but it only has a Core 2 Duo 7350(?) processor. I am also thinking of a desktop, and possibly getting a netbook for internet access upstairs. The Dell Studio XPS looks good, and will be roughly the same cost as the Toshiba with a monitor, but has a quad core processor. A local shop has quoted me about $1200 to put together a comparable system with Quad core Q8200 with Q45 chipset, DQ45CB mobo, 4gb DDR2 Ram and Asus Extreme EN9600GT 512mb video card.

My concerns are: how much processing power is required to edit SD video? If I go to HD video will I need the quad?
Are Dells upgradeable, say if I want to add a bluray drive in the future, or am I better off with a generic build for this purpose?

Thanks for any suggestions.