the bridge will most probably work, but some are quirky and may render the sb useless;
you dont need to slow down at all unless playing one of those games that will crash or run like flash sinning on faster machines;
p3 is a very good machine for late dos especially but old games will run too (some with tweaks);

plumbumber wrote:

Also should i try to underclock/slow down cpu or just disable L1 & L2 cache when playing dos games?

There is a pretty big list of older games that might require it (check this thread - it also has a link to a more comprehensive list in it), but even if disabling the caches do not work for you (making the PC too slow, or still too fast for some titles), an earlier P3 like this can pretty much run all of them at correct speeds when chipset throttling is also used (an uncommon, but very powerful method of making your CPU run slower). It just requires a bit of tinkering.

Which Deskpro is it? you may be able to get a different raiser card that includes an isa slot nativity.
You also have the option of getting a soundcard with comparability in windows, SB Live! and later are the common ones.
a P3 will have plenty of power to play dos games without needing to drop back into pure dos.
It's also a good system for Win9x gaming as well!