I don't know anything about digital recorders but I have been recording to my computer for quite some time now. If you really get into it here are some things you might want to look into getting.
-an echo soundcard http://www.echoaudio.com
-Cool edit Pro http://www.syntrillium.com
-Cakewalk Home Studio if you plan on doing midi recordings. If not then you would be best to go with cool edit
-Guitar Pro. http://www.guitar-pro.com
Works nicely for making drum beats and adding keyboard parts that you write on your guitar if you dont play the keyboard
-Mixers are very usefull. Definatly should get one. I like the Macki mixers the best.
-Studio Monitor speakers.
-If you are doing midi recordings the Roland jv-1010 external midi synthesizer comes in very handy. Very very nice instrument sounds.
Is that Tascam just a tape-deck recorder? If that is what it is and you just plan on using that then you will want to experiment with the micrphone placement. You will probably want to look into buying a better mic also. I heard it's best to put the mic at an angle parallel with the cone of the speaker. The distance away from it will determine how much highs, mids, and lows you get. The size of the room and how much it echoes will also effect your recording. You might want to try putting the mic close to the speaker then hanging a blanket over the speaker and the mic. That should give you a nice thick solid recording. I've never recorded with a mic though so I don't know for sure. I plug directly from my pod to my computers soundcard.