I wouldn't recommend running snort on the server machine you are hosting from , a dedicated machine running snort would be ideal so i'd advise setting up a seperate machine if your wondering about OS i'd say go with OpenBSD iv'e setup many NIDS boxes using OpenBSD n snort it's realitvely painless.

here's a tutorial I used when first setting up snort & ACID on openbsd: Tutorial it's written for OpenBSD 3.2 in mind but can obviousely be applied to the 3.4 and 3.5