If you do not intend to upgrade to DDR3, a Hybrid board that supports both DDR2 and DDR3 would be a choice for most.
Gigabyte GA-P35C-DS3R based on Intel P35 chipset makes it possible. This board has 6 memory slots. It can function in Dual Channel DDR3 (2 DIMMs) or Dual Channel DDR2 (4 DIMMs)
Read abt it here at
http://www.ocworkbench.com/2007/giga...5C-DS3R/g1.htm
Gigabyte GA-P35C-DS3R (Intel P35) Photos and Specs
Processor
Intel® Core™2 Quad/Core™2 Duo Processor
Support 1333/1066/800/533MHz FSB
Chipset
Intel® P35+ICH9R Express Chipset
Realtek 8111B GbE LAN
Realtek ALC889 8 channel HD audio codec
Memory
Supports DDR3 1066/800 memory
Supports DDR2 1066/800/667 memory
Dual Channel DDR3 supports by 2 DIMMs
Dual Channel DDR2 supports by 4 DIMMs
Expansion Slots
1 x PCI Express X16 slots
3 x PCI Express X1 slot
3 x PCI slots
Form Factor
ATX form factor (305 x 244mm)
Internal I/O Connectors
8 x Serial ATA 3Gb/s connectors
1 x UDMA ATA 133/100/66/33 connector
1 x FDD connector
4 x USB 2.0/1.1 connector (support 8 ports)
1 x Front Audio
1 x SPDIF_IN connector
3 x Cooling fan
Rear I/O Connectors
4 x USB 2.0/1.1
1 x RJ45
1 x Optical / Coaxial SPDIF_OUT
1 x LPT port
1 x COM port
6 audio jacks
PS/2 Keyboard/Mouse