Need recommendations & advice on building new Server box

Looking to build a new server box for my Lab.   Already have a SuperMicro case w/ 8 hot-swap SATA bays, 2 5¼ external bays, 800W redundant PS.  
http://www.supermicro.com/products/chassis/4U/745/SC745TQ-R800.cfm

Intel socket 775 Quad-Core 6700 (the G0 SLACQ version) is on order.   http://www.clubit.com/product_detail.cfm?itemno=CA1938458

Looking at P35 chipset motherboards supporting DDR3 memory.  Onboard RAID is a factor, although Ive been looking at an 8-channel Adaptec RAID card (Link:  http://www.newegg.com/Product/Product.aspx?Item=N82E16816103046 )  that offers more RAID options than the onboard RAID Ive seen.  For OS, Im Planning on Server 2003 R2 with eventual upgrade to Server 2008.  With 8 SATA bays available, Im thinking of using 2 mirrored WD Raptors (10K RPM) for the boot & system drives, then running RAID 50 using 5 WD 500Gb Raid Edition drives http://www.newegg.com/Product/Product.aspx?Item=N82E16822136143  keeping the remaining one as a hot-swap spare.  6 or 8Gb DDR3 memory at the lowest latency and fastest speed the motherboard will support.  Ill use a decent PCI-X graphics card, but I only care that it doesnt put a bottleneck on the system, since Im not planning on turning this into a gaming rig (though Im sure it would be smokin if I did).  Here are 3 P35 chipset motherboards Ive narrowed down to so far (though I may decide to wait for the X38 chipset& your thoughts are appreciated on this).

Another option is to use the second 5¼ bay with a Star-Tech SATA removable tray for a single Raptor for the boot & system drive, image it to the second Raptor in the drive cage, which would leave me with 7 remaining bays available.  The advantage of this would be to allow me to test install other Operating Systems while leaving the data storage intact on the primary RAID array.  

Here are 3 motherboards I've looked at so far:
GIGABYTE GA-P35-DQ6 http://www.newegg.com/Product/Product.aspx?Item=N82E16813128046
ASUS P5K3 DELUXE http://www.newegg.com/Product/Product.aspx?Item=N82E16813131181
ASUS Blitz Extreme http://www.bestbuybusiness.com/bbfb/en/US/adirect/bestbuy?cmd=catProductDetail
 
Ill plan on using a Zalman HSF http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=373519    (dont want to go to water cooling) and do some minor overclocking but keep within limits for longevity.   (Toms Hardware and TweakTown reportedly overclocked this CPU to 3.6, but I wont go quite that far so as not to kill the CPU through 24/7 ops at insane speeds).   The Q6700 is the latest rev and stock speed is 2.66.   Reviews Ive read indicate that it will easily OC to 3.0-3.2 and run stable and reliably all day long.  I'm already running a box with a Core2 Duo 6600 overclocked to 3.12 on air cooling and it's been running perfectly stable 24/7 for almost a year now, so I'd think the Q6700

Initial OS will be Server 2003 R2, for which I have a 10cal license.   I also have the beta versions of Longhorn and MS Home Server for testing and familiarity.  Current network is a 1Gb Workgroup only LAN w/ 3 Gigabit unmanaged switches (2 of which support jumbo frames).  3 systems running XP-Pro, 1 W2K system, 1 Vista Basic, 1 Vista Business, 1 XP Home.  The XP Home, Vista Basic and 1 of the XP Pro system will remain on the existing workgroup, with the others joined to the local domain.   My email and web are hosted externally and I plan to keep it that way, though I will install VPN and FTP.

Looking for thoughts, recommendations and opinions; mostly on motherboard and memory, but all other inputs & recommendations are welcome.
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