Please! Critique my Future System.. Best Choices?

Thanks for helping me out, this is my first time building a system and I have been spending hours trying to research parts to get etc.. I am using this system for work/word processing/gaming (of course)/multimedia/watch movies /multitasking and of course internet surfing. My budget is 1400$ maximum, so here is what I have so far. Some of my concerns are listed, let me know if they are feasible or if I shouldn't worry. Also, if you can, please list specific choices that would be better then the ones I have picked.

Case: Antec Lifestyle SONATA II Piano Black Computer Case (Comes with a 450 watt PSU, is this enough power for my system???? I heard my mobo is a power hog, so maybe I need 500 watts? It's also extremely! important that I get a case that is very quiet.. noise level is a huge factor because I'm a very light sleeper and can only sleep with quiet, and I'd like to leave my computer on at night, my concern however is this case will NOT provide adequate cooling for the parts that will follow, and I don't want anything burning out)

MOBO: DFI LanParty UT nF4-D Socket 939 NVIDIA nForce4 ATX AMD Motherboard (I wonder if this board will work with my CPU choice? Also, should I get SLI compatible MOBO?)

Processor: AMD Athlon 64 X2 4400+ Toledo 1GHz FSB Socket 939 Dual Core Processor (Heard this is solid, good for my price range I guess)

Memory: CORSAIR XMS 2GB (2 x 1GB) 184-Pin DDR SDRAM Unbuffered DDR 400 (PC 3200) Dual Channel (is this memory solid? should i get something better/faster?)

Video Card: Geforce 7800 GTX

Hard Drive: Western Digital Raptor WD740GD 74GB 10,000 RPM 8MB Cache

DVD/Rom/Burner: Nice NEC one

Well that's it.. please tell me if you spot any potential problems, such as heating issues, sound, or compatability, as well as if you think it'll be a solid system with those components. Thanks, your help is much appreciated.

I'd say an X1800 XT over a 7800 GTX also, unless the 512MB version drops a few hundred.

Is my 450 Watt PSU enough power for this system? Also I've heard the 10,000 RPM raptors are noisy, i wonder if using one of these will compromise the "quietness" of my system. Do you guys think that this case will keep the components cool enough?