Since mATX boards are relatively inexpensive compared to ATX boards I'd probably recommend the
Biostar TA890GXE ($115). The 890GX chipset is one of the best (which usually means the other on-board components are higher quality), the board's power system (MOSFETs) have a heatsink on them, and the board will handle any CPU up to 140W. IMO, all those make it as good or better than most mid-range ATX boards. (PS - There are cheaper boards but I wouldn't count on them lasting 4-5 years.)
For the processor, that depends on how much you want to spend. The
560BE ($109) is a dual-core and, at 3.3 GHz, is as fast as stock dual-cores can get. The
970BE ($195) is a quad and runs 3.5 GHz, while the
1090T ($253) is a six-core and runs at 3.2 GHz but will automatically boost itself to 3.5 GHz if only 1-3 cores have a high work load. If it were me looking 3-5 years down the line to the next machine I'd buy as much CPU as I could. (BTW - I checked and Cakewalk has been multi-threaded since, I think, v3.1.) Another option would be the Athlon II
645 ($121) at 3.1 GHz. It's slower than the other CPUs listed and doesn't have L3 cache (second-stage on-die memory) but it's also less money while still being a quad.
Add in $150-190 for a good PSU and 2x2 Gb of RAM and that covers what I call the basics - anywhere from $375-560 depending on your exact choices. All four of those would have to be upgraded at the same time. (Well, you could buy the PSU first - I think it'll work with your existing hardware - then the CPU, board, & RAM in one shot.) Your existing video card probably wouldn't fit the new board but it has on-board video that's probably better then what you have now, so you could wait to get the video card at a later date if you wanted/needed to do that.
I've tried to pick components based on your gaming & music editing needs and I've also taken into consideration that it may be another 4-5 years before you invest in your next computer. I picked the fastest CPU in each class based on the assumption you would not be overclocking, though the cost wouldn't change much, overall, or would go up (as would your performance). Hopefully this list will help you weed out the less desirable choices and point you in the right direction for a solid, long-lasting machine ...
