We use the free Sharepoint server. I would caution against using the built in Spiceworks Knowledgebase for a couple of reasons:
1. There's no way to get your data out if you need to that I found (we sync our KB docs offsite nightly).
2. If you rely on the cloud, you can be in a lurch when it's down for maintenance (which happened to us more often than we liked).
Just a note on point one, the data is just in an SQL database, if you have access to that you can get the data out. If you have hosted sharepoint this could be an issue.
