Basic recording system with Free Pro Tools Options

I am just starting out trying to get a basic, inexpensive recording system on my G3 Mac. I am running OS 8.6, 350 mHz, 256 megs of RAM. I have a Yamaha CD burner with Adaptec Toast software. I just want to record some voice and guitar. I have been told to get a Shure SM57 microphone and plug it directly into my CPU, then use the Free Pro Tools software. Does this sound right? Should I get a mixer or will the free Pro Tools work okay by itself? Any advice anyone can offer would be most appreciated!

[Presto]

Got sold a Sure SM58 when I asked for a mic that would handle sounds up to 20KHz for a home studio. I thought if I insisted on 20KHz the sales person wouldn't sell me less, but when I got home I read the specs - at 10KHz it zooms down and disappears at 15KHZ.

With Protools Free and no extra hardware, I think you are stuck at 16bit recording (OS9 sound manager) so you don't need a 10,OOO€ mic, but you can get something more appropriate than the SM57 (which everyone says is great for stage performance). Its true the good mics require phantom power but some will accept a simple AA battery.

Try the Microphone University at www.dpamicrophones.com for understanding the specs (DPA push omnis - maybe they are right). There are loads of mics at www.fullcompass.com where you can download the catalogue - I just did, and am still struggling.

Best of luck!!

PS the shop took the SM58 back in exchange for a pair of Beyer DT250 phones (and a few euros more) - wow :-)).