trabis

Hi all,
I am an 'having problems' customer of another hosting company.
Here is a short brief of my site history.

Started with a shared hosting on an a very small hosting company.

Site grows over 10 gb traffic/month and I started to have problems so I moved on to another shared hosting on an international and famous company.

All went well until I started to have around 80 gb traffic so I
Moved on to virtual dedicated server with cpanel and 256mb Ram. I had imediatly upgrade it to 512mb because he could not handle more than 100 user online.

All went well for two months or so. Now vps is acting strangly. Some times I have a low cpu load with 150 users online (1.0-3.0 on a quad) and some other time it peaks over 30-40 until it crashes. I have spent my last weeks rebooting the server and sending help tickets.

I´m of sick of it. One day all goes fine, the other day server goes crazy.

At this moment I have aroun 150Gb traffic /month. I use xoops cms so It is database intensive. Around 50 queries/page. Some times I have 250 users online.

So my question is (I´m a newbie on this) :

Wouldn't a Vps take care of this single site?
Do I need to go dedicated?
If so, would a celeron handle this database number of queries?

If I need suport will you say more than:" Everything looks fine here, please review your queries and optimize your code."?

Thanks!

Ps: Surpass was recommended by some xoops users. I also know surpass hosts xoops.org and xoops.org activity is prety like my site so, what is xoops hosting plan here? Maybe I could have the same configuration.