Not able to decide the mobo chipset

Well i generally avoid anything Nvidia, VIA and SIS because of lifespan, reliability and compatibility (dont have a go at me for listing Nvidia please, im a systems integrator - try making common UT installs for a wide range of nvidia products and see what hassles you have before even thinking of having a go at me for saying that)

For Intel processors i would stick to Intel chipsets, and for AMD processors i would stick to AMD/ATi chipsets

As for motherboard brand - you cant really go wrong with ASUS or Gigabyte

Also concider an i5 or i7 rig, or even an AMD Phenom II X4 or Athlon X4 etc - whatever best suits your budget, and look for the best bang for the buck.

As for 64-bit - just about every 32-bit app will run on a 64-bit OS so dont bother with a 32-bit OS especially with that sort of spec system - go atleast Windows Vista x64 (with free windows 7 upgrade).

Apps may not take advantage of 64-bit and the vast amount of memory supported but at least every 32-bit app will get alot more memory (4gb max per app etc) rather then everything crammed into the 4gb limit, and i believe the newer versions of photoshop even come with a 64-bit part now as well.

Best of Luck

Ydafff over in the anandtech "for sale" forum has 2 new boards for sale discounted. One is the Intel G45 micro atx, which is a legacy board (no ps2 ports for keyboard or mouse) and an MSI p43 neo-f atx, which is a standard no frills board, probably from a recent Fry's combo. Or, checkout the asrock p45ts ($75 at newegg) which I've used. It's also a no frills p45 board.