Water-cooling is the easiest of the three, and probably enough for what most anyone would need. It will keep your T-Bird running just a few degrees above ambient temp. There are a lot of places that sell water-cooling kits. There are a lot more, I just can't think of any right now.
<A HREF="http://www.senfu.com/" target="_new">http://www.senfu.com/</A>
<A HREF="http://www.swiftnets.com/" target="_new">http://www.swiftnets.com/</A>
<A HREF="http://www.3dcool.com/aquastealth.shtml" target="_new">http://www.3dcool.com/aquastealth.shtml</A>
If you don't know much about peltiers then I wouldn't even consider using one yet. You can really damage your CPU, and /or your power supply.
If you have the money to spend on it, then vapor phase is probably the best. This can get your processor to about -20C. Even an Athlon.I only know of two companies that make kits. Aztech's Vapochill kit sells for about $650.
<A HREF="http://www.kryotech.com/" target="_new">http://www.kryotech.com/</A>
<A HREF="http://www.asetek.dk/" target="_new">http://www.asetek.dk/</A>
Read up on it and decide for yourself what you want to do.