I would have a custom dedicated music PC built. There are a selection of pre built suitable music PCs on the market specific for music production and most PC builders could build one to your specs. There will be no need to worry about external interfaces etc as these would be built in with your sound card. The benefits of such a system far outway the extra cash outlay and hassles of trying to multi task a conventional multi purpose PC. The biggest probs with home recording are latency and extraneous noise. These probs are all but eliminated with a custom built PC.