After doing some moderately in-depth research on subject and after playing for a couple of years into my soundblaster, here's what I've come up with:
Pricepoints:
Low-end: the typical instrument direct into the SB card - poor signal/noise ration since you are attempting to put an instrument level signal into a device that is expecting a line level signal; cheapest option. All you need is a 1/4" to 1/8" adapter - plug yourself into the card's LINE input. You'll need free or cheap recording software - n-track, ProTools LE, Tracktion, etc.
Mid-level ($100-500) - typically a dedicated outboard or onboard soundcard (PCI, USB) with limited inputs and connectivity. (ie. Tascam US-122, M-Audio MobilePre). You can get by with free or cheap multitrack software, or you can use the stuff that gets packaged with the hardware. Otherwise, you can choose any mid-level recording software (i.e Cakewalk GuitarTracks Pro v.3 is great if you don't need MIDI support). Supports multiple connectivity: 1/4", XLR, etc. Low latency (software) and no latency (hardware) monitoring. Pro features, but limited capacity (tracks, inputs, busses, etc)
Upper-Level ($1000+) - now you're getting into the realm of multi-thousand dollar setups - outboard mixer, firewire connectivity, multiple channels in and out, high end software (ProTools). No latency software/hardware monitoring. Excellent quality, pro features.
I just recently went from the SB card setup with n-track and am now using M-Audio MobilePre (USB) with Cakewalk GuitarTracks Pro. 2 channels in, low latency (software) no latency (hardware), 1/4" and XLR connectivity, onboard preamps, headphone out, very quiet. Paid under $400 CDN total - not including a up-to-date laptop (P4 1.2Ghz, 40Gb, 512Mb ram). This setup gives you much better quality than cassette based 4-tracks, with VST plug-in support, 32 "real" tracks, full featured mixing board with busses, etc.
I'm getting pretty good results.
A good resource for more info is
HomeRecording.com
DD