From what I know and have read in the guitar catalogs, etc. there are cards that go in the PC which you can plug various gear into - mics, guitars, keys etc. and those cards generally have a cable that breaks out the different connection types, e.g. XLR for microphones, 1/4" phone plugs for guitar and keys, RCA jacks for CD players and such. Then there is software that runs on the PC, communicates with the card and allows the simultaneous playback and recording of audio on different tracks, saving of song tracks, adding of effects and so on.
There are other similar devices, with added capabilities, based on firewire, where a card goes in the PC and a fiber connection is made to an external box which has all the various connectors and provides buffering, etc to help eliminate problems that can inately occur when using a direct PC card interface.
I also believe that there are some lower end connector devices (for lack of a better term) that can plug into a USB Version 2 port on the PC. These would provide similar functionality as the high end firewire devices w/ software included to provide the recording and mixing. If your PC is more than a few years old, then it will probably not have USB V2 and USB version 1 would be too slow to function correctly.
I do not know of a direct USB converter cable for a regular guitar, but have seen USB capable guitars produced specifically for this type of application. Perhaps there are powered adapter units that will take the 1/4" phone and analog guitar signal and convert to a digital USB signal for the computer.
As far as the sound card, they usually have a mono mini plug for a microphone and a stereo mini plug line in for connections to stereos, etc. This line in could be used in conjunction with a mixer of some sort and thus support mics, guitars and keys. As you have mentioned, you could mic your amp and likely assign the microphone input from the sound card as the input to a recording application then switch that microphone input device between channels, but I cannot be sure on that. Depends on the application used.
I agree with the statement that a digital recorder w/ x number of tracks is better than the tape unit of the same type. I have a 10 track digital unit that features two input devices (XLR or unbalanced phone). The music is recorded on a hard drive. My unit also has a USB connection and software to interface with a PC. I have done things like... recorded my band w/ a DAT deck, dubbed the DAT recording (using a specialized audio capture card) onto the PC, transferred the song to the recorder deck on a stereo track and overdubbed vocals on additional tracks. Fun stuff!
The one thing I found limiting on this setup is only having two inputs and I've hit that issue with wanting to have more than two singers each with separate mics, but if you are using this for only yourself, the four track one you mentioned should be no problem. but do thinnk about how many tracks you might want to record.
There are many ways to go. So I have a digital recording deck that is portable. It is somewhat low-end and I could use more but it works. I keep the PC free of being the interface recording medium because it is not portable and you are restricted to the local area the PC is in. Trying this w/ laptops, via some USB device will almost certainly produce lessthan desirable results, you need a decent PC and a good interface card on a high speed bus.
People do successfully use the PC as the recording and mixing device, no problems there with the right software, hardware and PC. It really depends on what you want to be able to do with the setup and how flexible you want it to be.
My advice is to look around
www.musiciansfriend.com and
www.samash.com and check out the various offerings and think about what you want to be able to do. The information should help you make an informed decision.
Good luck,
Dave
" smith