just a few suggestions...
ok, im not an expert but ill share the few bits of advice i have. im assuming you are fairly new to digital recording, if not then please forgive me:
1. find out what kind of software you are interested in (if you are just starting out it may be best to buy something cheap to get you started, pro tools isn't difficult but can be daunting at first).
2. once you know what kind of software you wan't look up the specs it needs to be ran properly, u can find this on most websites and the box, if you aren't familiar with computer language and don't understand how many rams, gigs, etc then take a spec sheet to best buy and they will be happy to help you find the right pc. In my opinion the best pc is not the way to go, get something that will properly run the software and give you enough room to record songs and store plug-ins, then u can spend the rest of your money on goodies!!
3. make sure you have all of the proper cables and connectors for your setup.
4. good monitors, these are crucial if you wan't to make something with decent quality.
5. Plug ins, downloadable software that you can use for various editing, mixing, and recording effects... unfortunately these are fairly pricey.
just a few of my opinions from trial and error getting my own setup going, again if ur way past this then plz disregard my info.
i run protools mpowered 7 on a dell inspiron e1505.