BIOS.
Basically it's the firmware that runs your motherboard. Most newer motherboards you can flash via a bootable USB. Older ones, personally never tried, but iirc you can do it via CD.
The alienware desktop you linked to is a waste of money. If you get it, you will end up regretting it. An i3 processor just doesn't cut it for me personally. The ram is a joke. You're basically paying a hefty premium for the nice looking case.
Lastly, the processor you want is not very cheap. Yet it is rather old, and outdated.
Passmark.
It doesn't even touch the high end CPU's.
Link.
If you're patient, you can build yourself a decent computer for not much more than it will cost you to upgrade ram, and cpu on yours.
@BB - If you're using 6GB basically idling, some services you don't need are definitely running. Most of the time I'm under 3, even 2GB when not doing much. For example, right now, using 2.5GB, I have chrome open with 10+ tabs, WMP, digsby (chat client), couple of folders open, and chat client. Usually also outlook, excel and rdp, if I'm working. Only time I'm past that much, is if working with specific programs, or gaming. Even than I don't think I ever hit capacity.
About pagefile... I don't really see the point in disabling it, unless you're using an SSD. I've tried it, didn't notice any difference.
One thing that I would like to try with my next build, probably in 2014, or 2015, will be a ram drive. Right now 8GB sticks can be had for under $50.
Of course the way we're headed, we're also likely to start seeing ram and hard drive (SSD) become integrated, just as we see that same trend with intel and amd adding graphics capabilities in. So idk if when we do start seeing higher capacity ram (16gb, 32gb, 64gb) that it will be quite as cheap.
For the moment, few programs actually require anywhere near that much ram though, and until they do, we're not going to see much speedy progress. Same with LCD's... 1920x1080 monitors are dirt cheap now. I would love to more high def displays start to show up... not going to happen anytime soon though. Most people are still perfectly content with even DVD quality
Edit: In college, ~2002, I was perfectly happy with dvd quality though