630 vs 730..21 lbs?

The 730 is also physically larger than the 630 so more metal all around. My box is the size of a dorm room refrigerator, and as you mentioned the PSU is bigger, the HDD cage is bigger, motherboard has more stuff on it... box is bigger, more free stuff in the box...

Video card may also be bigger depending on what you got, I am guessing that the CPU cooler may also be bigger too.

and the 730 has a metal and plastic stand which adds significant weight.

_____________________________________________________
XPS 730 Air Cooled
Windows Vista Ultimate x64
Intel Core 2 Quad Q9550 2.83Ghz @ 3.4 GHz
Nvidia 9800gx2 (1 for now)
4 GB 1333 Mhz Dell Memory (for the time being)
160 GB WD VelociRaptor
1 TB WD Caviar Black
Dell Bluray Burner
X-View Side Panel
Dell 2408 Ultrasharp Monitor & ViewSonic VX922
Microsoft SideWinder Mouse
Logitech G15 Keyboard
SoundBlaster X-Fi xtremegamer (D) (No more crackling and Popping during gaming, but still crackles when scrolling and playing music in SLI mode)

XPS730 fan...

My rig is very simiar to yours with the difference being an Nvidia 260 replacing your 2x gtx's.

How do you like it? I cant wait until i get my paws on mine.

I Love it and would take it to bed with me every night if it didnt weigh so darn much. Never any problems with it and its really impressive and quick. I had been drooling and wanting one for a long time and it was worth the wait. Welcome to the club !!

Model: XPS 730 Air Cooled
Operating System: 32bit Windows Vista Home Premium
Processor: Core 2 Duo E 8400 3.0 GHZ @ 3.6 GHZ
Graphics Card: Dual 768MB 8800GTX in SLI
Monitor: Samsung 22”
Memory: 4 Gigs Stock Dell Memory@1067
Hard Drive: 750 Gig Sata Drive
Sound Card: Creative Sound Blaster X-Fi Xtreme Music
Power Supply: 1KW Power Supply
Other Components: Lightscribe Burner
19 in 1 Card Reader with Bluetooth
Logitech Z5500's
16,593 3D Mark 06 Score

Curious why you returned the 630.  I configured the 630 and was close to purchase but research of it on here and google has made me very scared to pull the trigger.  It looks like the 630 issues that can be addressed are, but it also appears that the hardware was intentionally crippled by Dell.

I am considering the 630 because of the xp to vista ultimate program.  Not sure if the 730 will take a 32 bit xp install/drivers available.

I really should of returned it the day I got it. It came DOA. But noooo, I had to try to fix it.

My 630 came with 2 ATI 3870's in crossfire and the Dell techs could not get the Cat. control center (CCC) to work. This is the only way to turn on the 2nd card. 

Now I have read that Dell had a special version of the Nvidia 650I motherboard made so both ATI and Nvidia dual cards could be used using Dell's video driver. The problem was, Dell didn't seem to have a Vista 64 bit driver that allowed the CCC to work.

Dell then gave me $125 "shut up and keep the PC" money to get a new card. Between that and knowing I could sell the 3780's on e-bay, I decided to get a Nvidia 260. When I got it, I was surprised that the performance was good but not great. This is when I found out about the PCI-E speed issue. Normally this motherboard has 2 PCI-e vidoe slots in either 8x by 8x for dual cards or 16x for a single card. As I found out Dell's motherboard runs a single card (like I just bought)at only 8x! I read that people were saying it's not that big of a deal...maybe a 10-15% hit based on benchmarks conducted 6 months ago. Here I was, with a cutting edge card trying to play a cutting edge game (Crysis-Warhead) and I could see the difference.

Luckily enough people had complained that Dell (quietly) allowed unhappy 630 users to return their PC's after the standard 21 period.    

Now I have had Dell's for over 10 years with no problems at all. I bought the 730 the same day I got the RMA for the 630. The 730 has a totally different MB (Nvidia 790i chipset) that has full 16x speed (even for dual cards).  

It's coming today so I cant tell you how it really works yet.