I used the following site to configure a dedicated front end server for crawling:

http://technet.microsoft.com/en-us/library/cc261810.aspx

In doing this, the only issue I ran into was this error:

The search service is currently offline.  Visit the Services on Server page

in SharePoint Central Administration to verify whether the service is

enabled. This might also be because an indexer move is in progress.

My issue was related to the existing server having a file index location of C:\Index.

Central Administration > Application Management > Manage this Farm’s Shared Services > New Shared Services Provider

Once I created a folder in the same location, on the new server, the error went away.

Only thing I can imagine is SharePoint wanted to move the index from the old server to the new server.  SharePoint being SharePoint, it wanted the index folder in the same exact location.

Update:

If you are moving to Windows Server 2008 make sure you read this KB article.

Access is denied. Verify that either the Default Content Access Account has access to this repository, or add a crawl rule to crawl this repository. If the repository being crawled is a SharePoint repository, verify the account you are using has “Full Read” permissions on the SharePoint Web Application being crawled.(The item was deleted because it was either not found or the crawler was denied access to it.)”

http://support.microsoft.com/kb/896861