The E8400 is plenty powerful enough. I consider the 2GB too little but others will argue.
Will you be using the HTPC console session or solely extenders? If I have my console + 2 extenders in use my memory utilization ranges from 2.8 GB to 3.6 GB. The console session’s ehshell.exe takes up almost double of what an extender session uses so if you aren’t planning on using the console session (i.e. the HTPC is headless) then you may get by.