I'm planning to build a computer for doing my music works, (and maybe a bit of gaming.

) Is there anybody here that is familiar with professional audio hardware? If so, can you give me suggestions on how should I build my computer? Which audio interface do you think is good that is not too pricey?
I'll be using Windows XP (sadly), with Nuendo. I'll be doing a lot of MIDI also, but my keyboard is using a USB connector. I'm a student, so I'm looking for something affordable.
As for the sound card, one of my friend is using ESI Juli@. Should I buy that too? or an external sound card would be better? I will not take M-Audio, because they force me to use ProTools, and its way too expensive.
Thanks.
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