Communication with HD is never going to be instantaneous (even quantum computing will impose interesting time constraints) . . . somewhere between 25 and 33 ms is when the 'lag' becomes noticeable, roughly equivalent of 43-62 ft with genuine slap back echoes possible at 55 ft. so you start daisy chaining nearly imperceptible delay on successive tracks and it becomes noticeable fairly quickly . . . beat frequencies among 'close' but not sync'd tracks becoming noticeable before actual 'delay'
Analog recorders deal with a lot of the same issues (with fewer tech 'fixes') but since the 'delay' is fixed by distance between record and play back heads (and speed of tape) the artifacts are a bit different (but can be just as messy . . . SWS vs. SOS)
general purpose computers, no matter what their 'speed' specs are not configured to execute the kind of thing you are talking about. modern consumer OS have been optimized for static data . . . anything that can be buffered & packet switched . . . rather then simply trying to correct the issues with 'faster' hardware (which might ultimately be necessary depending on goal) is seldom the most effective approach. Multiple HD's (getting audio off the OS drive) making sure (even today) that things are operating in DMA mode, making sure you are using the most robust drivers for audio gear, disabling read/write caches, disabling as many superfluous (to audio goal) OS 'calls' (time sync's, palm sync's any & all background network, any & all Anti mal ware supervision, any and all firewalls, etc). making sure your HD's are capable of the demands, even with NTFS fragmented drive, with regard to streaming data, is still a fragmented drive . . . an OS (Vista) that does not release memory, CPU cycles efficiently, software that fails to release memory can all compound basic hardware issues
so while we have refined how to accomplish what you are trying to do, yes it is actually pretty difficult and has required decades of collaborative effort to make it affordable . . . but something like
the Fostex MR8HD might be a cost effective solution more amenable to your goal (standard disclaimer: no affliation with fostex or any retailer, etc.)