I have run Snort on several different distros and can honestly say, it doesn't matter. What does matter is RAM, and a good Processor. While I have successfully used Snort on a Squid Server running a PII-233 w/128MB of RAM, it really performs better on a nicer machine.
And remember, send the logging to a database NOT on the Snort machine, with insert privileges only. That way your logs are secure and won't likely be tampered with.