[Super Jinni]

Thanks Deceptor for your helpful answers.
The reason to use Memcached with XCache is that I've set Nginx in front of Apache for static files, and read somewhere that it's good to set Memached behind Nginx so Nginx will check Memcashed for request firs, if not found there then it will pass the request to Apache. So I set Memcashed behind Nginx, but I couldn't make it to store data, so I thought I'd use vBulletin datastore, and it seems that works so Memcashed now is cashing data while Nginx is pulling data from Memcashed if they are existed.

I'm not sure if what I'm doing the currect thing (Nginx (as font-end for static contents) + Memcashed (to cache for Nginx) + Apache (as back-end to deal with PHP) + PHP (mod_php) + XCache (with your vBO))

I'm worried about performance and server usage, so if you have any suggestions or ideas regarding what I use and how I use it, please let me know.

Thanks