Depends what you mean by 'mid range'. How much do you want to spend?
What kind of computer do you have? Is it PC or Mac? How much RAM and storage do you have?
Are you talking mics, mixers, preamps, keyboards, monitors, plug-ins, software etc? Or do you just want something simple to record your guitar?

Multitrack or computer depends on the level of recording you're going for and what purposes you'll be using it for. If you're recording a live band or just guitar, you may want to go for a multitrack. If you're wanting to sound like a pro or release a CD, you'd be better off with computer recording.

Audio interface and sound card are basically the same thing but again there's differences.. the sound card may have it's own processing power for things like plug-ins... or the audio interface may be a simple a/v input for your specific computer with it's own built in sound card... or it could include midi inputs and firewire

For less than $1000 you can get a used PC, a sound card off ebay, a small 4 channel mixer and Audacity or something.
For $2500 you can get a bare bones PC, a sound card, Pro-tools LE, some plug-ins, a decent mic, a preamp, keyboard controller and monitors.
Or you could get a Mac Mini in place of the PC.
For $5000 you can get a proper PC workstation with mega gigs and ram, a sound card with a mixer built in, Cakewalk Sonar, really decent monitors, preamp, a great mic, and plug ins. Or replace the PC with a Mac G5.


The difference is gonna be the quality of sound you'll get and the versatility.