well......
if 2 outputs of audio are enuff for you, and you're happy to mix those 2 outputs as 2 channels on a mixer with your external midikit, then a software such as Cakewalk pro audio version 5 is easy to pick up secondhand, and will give you plenty of audio tracks..... however, apart from eq, there are no fx... so to add reverb etc to audio, you need to add that on a mixer.... so that means with only 2 outputs, you are limited to 2 seperate audio outs, or a stereo out........ a pc to run that software with about 8 mono tracks would be a P100 - 166 with about 48 - 64 mb.....
now.... if you want to run say Cubase VST, or Cakewlk pro audio V6... these both have built in reverb, delay etc... so you can add these fx to individual tracks and therefore the 2 outputs is less of a problem, cos you can add fx internally, and happily use the stereo output of your soundcard, whilst still achieving seperate reverb or delay amounts on audio tracks....
or.... these programmes also address more than one soundcard, or soundcards with more than 2 outs...... so you could add a multi-output soundcard such as the Event cards, and mix all your audio on seperate mixer channels.........
however..... to run these softwares, you need a much faster machine, and ... there is a lot of disparity between systems, and realised audio tracks.........
if you go for an AMD 233, this will be cheaper than intel... trouble is, nearly all the motherboards come with TX chipsets...with Intel or AMD, the TX chipset slows down your system if you use more than 64mb ram... but 64mb, should be ok to run VST or cakewlk V6....... I have 2 mates with AMD 200's... and they are both getting about 8-12 tracks of VST audio....(with a few glitches here and there)
Ok....... so.... if a few audio tracks are ok for you to add to your audio samples, and you're happy with 2 audio outs, then a lower power pc, with the terratec card will give you 2 audio outs, and also outs for your samples... 4 in total... these can be blended with your external midi device audio outs on a small 8 or 10 channel mixer such as a Soundcraft Folio or whatever....for this, an older software such as cakewalk Pro Audio V5 will do the job....
either way...... Ram etc has started to go up in price again, due to the far east financial fiasco... so you can blame the chinese for that...... I can get an AMD 200 with 64 mb, and about 4 gb drive for around 650 (uk sterling) without monitor.... but where you are it's maybe more ?... i dunno...
if you then add the terratec, you'll have a sampler too and a synth.....
so it's your call...... a cheaper pc, with only 2 audio outs + the sampler outputs, with mixing for fx done outside the pc...... or a faster pc with internal Fx processing.......
bear in mind, there's gonna be a small price drop in intel chips around the end of January, with most of the lower power MMX chips discontinued in march..... at this point, there'll be another Intel price drop....AMD's will probably drop abit too then....... so it may be worth holding out a bit..... however, No-one can predict what will happen in the pacific basin, and ram and other hardware prices may be driven up nullifying any chip price drops...... I dunno ?.....
but... that is basically your options...... the Terratec will be about 400 - 500 in dollars or Uk sterling depending on dealer...... the pc ?...... dunno how cheap you get them, but to go for the VST or Cake-6 package, maybe you should increase your budget to about 1000......
but....... about 8 virtual audio tracks, with 2 physical outputs is fine for alot of dance stuff, and adding the sample outs to this, gives alot of power, if this is ok, then even an older P120 will do it ok.....remember, the sampler is triggered from midi notes, and these place little strain on the pC CPU & ram..... so the sampler card will deliver lots of audio up to it's ram limit, regardless of your pc power.....
the terratec... or whatever soundcard you get, will output your midi data to your external synths, drum boxes, modules etc... no need for a seperate midi card..... the terratec has 2 midi outs... each handling a full 16 channels.....
lastly, all sequencers take time to learn...... a s/ware sequencer is no harder or easier than a hardware one........ just learn it.....