sir kit, binabasa ko kasi mga previous posts niyo dito, ano po ba ibig sabihin ng paga-assemble ng PC depende sa software? paano po malalaman kung ano ang kailangan ng software? pano kung sonar 7 or protools?
Sonar, for example, has a minimum requirement: at least 1 GHz processor with at least 256 megs of ram. Understand that if you follow these specs, your computer will most likely crawl or grind to a screeching stop if you follow this minimum so it's entirely reasonable to expect that you should multiply the minimum values by at least 1.5 if you want to be able to do SOME audio work with your computer. Add the fact that Sonar is windows only so this somehow directs your hardware choice, although you can run Sonar on a Mac using Bootcamp, albeit with a few limitations.
There are software that are dual platform, Cubase/Nuendo, in particular, so choosing either Steinberg product will give you some flexibility in choosing your computing platform. Other software such as Logic Pro and Digital Performer are Mac only so that definitely mitigates usage in a PC. ProTools is also dual platform, btw, but the HD version of PT is so very specific with hardware requirements that it's almost mandatory to use Macs in order to avoid hardware issues. That is not to say you can't run PT on windows, but Digidesign is really picky when it comes to windows hardware.
Another factor is the soundcard. Some motherboard chipsets have issues with soundcards. For example, if you intend to use a firewire audio interface, the firewire chipset of choice is Texas Instruments. This is not some urban legend, but was arrived at by several respected DAW builders who experienced glitches with other FW chipsets such as Via, Agere and Ricoh (although Via seems to be on the rebound lately). On the pci card side, Intel's P35 is emerging as the chipset of choice nowadays, superceding the former P965 and 975 chipsets. Another thing is that pci soundcards are SLOWWLLLYYY transitioning to pcie. Some mobos only have 2 pci slots while the newer Intel X38 and X48 mobos have absolutely none, so getting a pci soundcard for an X48 mobo is just plain... you know. One more thing... some soundcards, such as Apogee's Ensemble, are Mac only so that definitely dictates your choice of computer hardware.
DAW software developers usually publish a list of recommended soundcards for their products. Cakewalk, for example, has a list of approved soundcards and listed issues with some cards previously. Usually, this is not a problem since soundcard manufacturers often release driver updates to correct these issues.
If you want to see which soundcards are usually recommended with certain DAW software, go to their user forums. I lurked in the Cakewalk forums for a year before I developed my present DAW.