I have socket 775 Q9400 CPU, for which I need to choose mainboard. I know some criterias which I have to follow(Intel chipset, FF ATX, DDR3, number of SATA, USB ports, Ethernet ports, etc), However, there are so many choices of Intel chipsets like P45, P35, G45, Q35... how can I choose which one suits me the best? What kind of features each chipset have and is there any site to compare those features for different chipsets?
How I approach these things is I look at what boards really are available to me (that I can possibly use). Then I filter to just those made by companies I like (I prefer Intel motherboards, simple and well made).. Then filter to those with features I like best.. I usually find by about this point I've got like 1 board that fits the bill for me.
If you really have a lot of options, then you can use this page to see differences between those chipsets. One metric I'd look to first is to compare their relative release dates.
Hope that helps ya.