Hey, im building a franken-puter, and i have one that has a dual core 2.8 ghz processor, but less room to upgrade and some other unsavoury things, and then a different computer with a single core 3.0 ghz processor, with better expantion slots and such. I dont have money at this time to get a new mobo or cpu or anything, so i was wondering which one (in your opinion) i should go with...
the two base computers im working with (upgrading things like RAM, HDD, and graphics) are a Dell XPS 200 and a Dell Precision TM Workstation 370
Go with the dual core since it will be much faster for parallels, multi-tasking and general computer usage. It also probably has more instructions per clock making it faster even with single threaded applications.
Intels 64bit started with the Pentium 4 5x1 series based on Prescott.
And to the OP, yes you need a 64bit OS to fully utilize all 4GB of RAM. Without it, you can only use 3.25GB to 3.5GB due to 32bits limitation of only 4GB total RAM (meaning system RAM, caches, GPU RAM) which all adds up. If you ahve a 1GB GPU then normally you get 3.25GB of system RAM. If you have a 64bit OS, you can support well more than 4GB (Something like 16,000 Terabytes of RAM) so it doesn't matter.