New guy needs help

I will try to make this short, as I know lots of words will be skipped.

I want to buy a Dell XPS. I am heavy into gaming. I had (in the past) bought a Voodoo PC (loved it), and tried an Alienware Laptop(sucked, thing didn’t even work and benchmarks were ½ of my desktop that had ½ the RAM and ½ the chip speed.!), and now I am looking at Falcon NW, Dell, and Ibuypower.com for new PCs.

I can make my own, and have, but my Voodoo lasted 3 years which was great in hardware years, but now the cheapest Voodoo is like $4k as I want it configured! >.<

Falcon is expensive and someone warned me about Ibuypower, so my only other option was Dell (unless I want to make another PC, which I don’t.)

My main questions are this:

1) Is a Dell XPS Desktop a good choice for FPS, MMO's and other graphically intensive games on the market today, or should I save for that Voodoo/Falcon?

2) They only use Intel chips, but is a dual Core Intel 3.0Ghz the same (except the 64bit architecture) as my 3.0Ghz P4 now?

3) Is it possible to squeeze more horsepower out of the stock motherboard with any BIOS options? I know they use Intel boards too, but sometimes manufacturers don’t "tweak" settings. I am NOT talking about overclocking anything, as I don’t see the long term benefits of this.

4) Is it (The XPS) as loud as I have read?

5) What is the difference (if any) of Pentium D 930 (3.0Ghz) Dual core and a Pentium 4 670 with H Threading running at 3.8Ghz? If a dual core is better why is the P4 670 an extra $300?

My dell config:

Dell Dimension XPS 600
Pent D 930 3.0 GHz Dual core
Windows Media Center 2005 (for use with my XB360)
2GB DDR2 533 MHz
512 MB Nvidia GeForce 7800 GTX PCI-E
Ageia PhysX Accelerator
Dual HDD
DVD-RW dual layer
And the rest is blah blah blah…
Total $2900 (about)

I hope I get some good answers and I have not bored you all to tears. If any of you out there have friends that can sound off I would also like to hear it. I really want to be educated to see if this would be a viable purchase for a hardcore gamer.

Oh and I also dont do any LAN parties, so no traveling is a factor.