Vostro 410 Ram Limitations with Windows 7 Ultimate - 64 bit

 I have a Vostro 410 with a The following as reported by the system.   I have only been able to get it to recognize 7 GB of ram when running Windows 7 Ultimate 64 Bit, but don't know if it is really utilizing it.   If I install 4 - 2gb sticks system wont boot all matching Corsair 2X2GG ddr2 800 Mhz 6400 matching sticks the computer wont boot and beeps  twice.  If I replace any off the 4 with a 1 MGB stick for a total of 7 the system boots and appears to run fine with Win 7 - 64 Bit Ultimate.  Question is am I really using all 7 gb and if so why won't it work with 8.  I have downloaded the bios from the site dated 7/15/08 since mine in a month older but the computer says I already have that version installed which appears to be correct ect. for the date.  Is there a upgrade to the bios to help out with the transfer to 64 bit?   Please help if anyone knows  with what the max ram is, the best configuration (i.e. 2-2gb sticks if 4 gb limit), fastest speed and maximum amount supported by board, processor, and chipset, and if dual-channel has anything to do with it.  I know there are a lot of people asking out on the web without a real definitive answer.

MACHINE INFORMATION

OS Name Microsoft Windows 7 Ultimate, Version 6.1.7600 Build 7600

Dell System Model Vostro 410, System Type x64-based PC, Processor Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz, 2400 Mhz, 4 Core(s), 4 Logical Processorr(s)

BIOS Version/Date Dell Inc. 1.0.3, 6/20/2008, SMBIOS Version 2.5

Hardware Abstraction Layer Version = "6.1.7600.16385"

PER SYSTEM REPORT

Installed Physical Memory (RAM) 7.00 GB

Total Physical Memory 7.00 GB

Available Physical Memory 3.88 GB

Total Virtual Memory 14.0 GB

Available Virtual Memory 11.2 GB

Page File Space 7.00 GB

Page File C:\pagefile.sys