It really depends on the length of the project. That recommended spec is probably good for projects that are 5-10 minutes long, but for anything over 30 minutes that system is going to be brought down to its knee very quickly. Instead of investing in more expensive hardware that will become outdated quickly, think about getting AspectHD as an alternate codec that's much easier to edit.
And don't spend a ton on a graphic card, they do very little to help you edit quickly. I would get 4 GB of RAM.
I've got a Dell 490 with twin XEON 3.2's and four gigs of RAM. Had been cutting some MXF projects for some time without issue using RAYLIGHT. Now that Premiere CS3 is "P2 Aware" with the latest patch I don't need Raylight any longer (or the CineForm product).
But you're using an A1, so back to your question: Premiere has become a fully mature NLE. Like Barry said in another thread, you get a lot of great additional sofrware with Production Premium CS3 i.e., AE, OnLocation, Encore . . .
While not exactly a "light speed" situation, I am also able to do rough cuts on a core duo 2gig laptop with 2 gigs of RAM. As suggested above a slow processor and too little ram can take a while rendering your final output--editing the timeline is not an issue. I think I would (as jade8472 said) upgrade your ram. See how that goes before jumping into more expensive solutions.
Dont buy a dell. They are very propriotary(not sure how thats spelled). Meaning that if you want to upgrade, your gonna have a hard time. Since your buying the big pieces of a pc, I would suggest getting a custom built pc. You will get more bang for your buck as well.
-If your gonna get a graphics card go with an Invidia 8800 series(work horse)
-Then you gotta have sufficient power for all those parts(probably 600 watts or more).
I tend to agree with Skiers187 -- BUT be sure to get your custom built PC from someone who KNOWS what they're doing. Main thing -- be SURE they use at least an anti-static mat, preferably an anti-static wrist strap too. I know, I know -- plenty of people will say, "I never used any of that, and my computers worked fine." Sure they did......for awhile. Then you started having 'issues', didn't you? Know why? Because that static electricity you discharged through your system when you were putting it together wasn't enough to kill components outright -- but it did weaken them, so in a few weeks or months they started failing or behaving erratically.
Anti-static measures are a must for anyone building, servicing or upgrading your editing PC. Unless, of course, you LIKE the idea of buying new hardware over and over.