Well, StillSecure has just put out an alternative to other open-source IPS/IDS products called Strata Guard Free. Strata Guard Free supports traffic streams up to 5Mbps, has a web-based console and several other enhancements over the freely available Snort.
Strata Guard Free seems well suited for SMB and remote offices. If you ever wanted to get your feet wet with an IDS/IPS its also worth a peek. Take a look at it here.