You'll need to change the operating system with a non acer board. At least acquire a new windows dvd and coa number. Newegg has a gigabyte g41 with two each of ddr2 and ddr3 slots for around $50. It will work with the newer core2 duos and quads. You may just want to overclock the q6600 with a different board. It's a pretty good cpu. Even some of the cheap g31 boards will overclock this cpu to 3.0 or higher.
Sure. Your windows 7 will install on any modern board with 2 gigs of ram. For overclocking, it depends on the board and cpu/chipset. Some you can simply change the cpu fsb. I use 240 when the default setting is 200 (for example). Some boards have the ram multipliers built in: you want the ram to run at the normal speed, so you can lower it by default or let the board do it for you. For example, I have one amd msi board with manual ram settings. I use 1:1.66 for the ram and 240 for the cpu, so the ram speed stays the same while the cpu is overclocked. Your settings may vary. You'll just have to experiment. If the board won't post after changing settings, you can move the cmos jumper over one position with the system turned off, then return to the original position, always keeping 2 of the 3 pins covered by the jumper. Or, unplug the power supply and remove the motherboard battery for one minute. That will always work.