Apache + mod_rails apache config

We have a 2GB memory xen setup with ubuntu, apache and mod_rails only (no db, etc.) -- is this a reasonable setup (taken from our apache2.conf )?

MaxKeepAliveRequests 390

StartServers 50 MinSpareServers 50 MaxSpareServers 50 MaxClients 400 MaxRequestsPerChild 0

What's the best way to optimize a server. We currently have 837 MB free ram with the above setup, so I'm debating add more Start/Min/Max servers.

Thanks.