My rig too old for HDV editing??

My computer (P4 3.2GHZ; 1GB RAM; 2 x 7200/8MB SATA drives) has worked fine for editing SD in the past (on Premiere Pro 2.0), but now I've captured an HDV project (shot on a Sony HVR), and PPro seems to "think" a lot while editing it. Granted I have put a lot of video effects on my test clip, which has slowed performance (and which I'll only apply once picture is locked when editing for real), but my QUESTION is:

Do I need a new computer (say dual core) to edit HDV with relative ease?

I realize another GB of RAM should help, but don't know if that's enough. Have been eyeing an Alienware 9750 laptop.... Thoughts??