Ok, you need to define your problem here.
Are you asking about:
a) Running a final mix into a computer and burning it onto a CDR.
b) Using your PC for MIDI recording. You mentioned your keyboard and "saving to a floppy" which implies MIDI.
c) Multitrack audio recording on your PC (live audio, guitars, vocals, etc many multiple tracks).
If the answer is:
a) Your computer is really on the verge here.
You basically have the minimum system requirements to burn a CD, and you might not have much luck burning at high speeds. The only way to tell is to buy a CD burner and give it a try.
You will also need a soundcard with a line-in port that can record at 16bit 44.1khz stereo minimum. You will take a line out from your tascam into the soundcard, and record a single stereo track onto the computer. For this you can use software such as
http://www.goldwave.com or anything that will allow you to record 16/44.1 audio. Depending on the actual ability of your machine, which entails much more than CPU speed, even recording one stereo track might prove difficult though. Also note that 16/44.1 stereo audio requires almost 10MB of space per minute!
If you're only talking about these very simple tasks, you could buy one of those nifty overdrive chips and perhaps a faster hard drive and possibly extend the life of your machine...but only for these minor applications.
b) Your computer can probably do a lot of things with MIDI. There is software out there that's similar to n-Track in price/performance but is geared towards MIDI...anyone know what it is?
Protracks or something? Argh, can't remember. Somebody help? You will need a soundcard with a MIDI port (typically doubles as a joystick port).
c) You're SOL unless you plan on keeping things ridiculously simple. Don't even bother upgrading that machine for this purpose because your money would be better spent on a new system. Assuming your PC really is a P133, you would need a new motherboard, a new CPU, new memory, a new hard drive, probably a new case, and in some cases a new video card. In other words...a new machine
As far as CDRW
vs CDR; always burn to CDR if you're going to distribute the CD's. Even though many newer CD players can play CDRW media, most older and some newer models will reject it. For your own use, however, CDRW is great media for working on as even 50 cents per CDR disc can get pretty expensive over time.
Slackmaster 2000