Missing Email in Outlook 2010

I helped out a buddy of mine who is a CPA and is helping out a small not for profit with their taxes etc. He asked me to take down their server because they are not really using it and it has just become a pain for them to maintain and to backup data. They went with a backup solution using Mozy so they really do not need this server anymore which is why he asked me to take it down and just create a very simple peer network structure since there is only 3 users in the office that access files on each other's system. The server was a bottleneck because it was an older Dell PowerEdge running Windows Server 2003 SBS, it was loud and an eye sore for these folks. I backed up all the data from the server on an external USB drive and took down the server. I reconfigured the network so the users workstations did not look for the AD DNS, DHCP and gateway. Everything is working fine network wise, but they are saying that they are missing a chunk of email messages that spans about 3 months. I looked through all their .pst files and I could not find the email that they say they are missing. Is there some tool that I can use that is able to search all pst files on a server and displays them in some enumerated fashion in a window or something that makes it easier to find these missing messages? Thanks for your help.