I assume that you were running your SI5 Server and the SI5 Client all on this one machine. If so, the data you are going to want to try to recover is your SQL data, which is your "server" data. This
post shows how to manually move your SI5 Server to a new machine and lists all the databases and folders needed. If you had projects checked out to you that had been edited when the machine crashed, you may need to re-import the project files (by default located here: C:\Documents and Settings\
username\My Documents\D-Tools SI 5 Projects) to make sure you have the most recent changes.
If you were not able to recover your "server" data, and were only able to recover your "client" data, here is the deal on restoring. You can manually copy and paste your local product database and images Visualizations folder into the same path on your machine (this will replace your product data, Setup tab data, and all product images, stencils, and blocks):
XP: C:\Documents and Settings\All Users\Application Data\D-Tools\SI5\MasterTable.mdb
C:\Documents and Settings\All Users\Application Data\D-Tools\SI5\Visualizations
Vista/Win7: C:\ProgramData\D-Tools\SI5\MasterTable.mdb
C:\ProgramData\D-Tools\SI5\Visualizations
For you local projects, you will need to re-import them via the "Import a project" function on the Projects tab within SI5.
There is nothing "local" regarding Clients and Contacts, that is "server" data only.
Hope this helps.