VPS, Colocation, & Memory

I'm looking to consolidate a half dozen hobby sites as well as one primary business venture website into one hosting account (1 main, 5 or 6 add-ons). I want to make sure I don't short change myself in the hardware department and I'd appreciate your opinions.

I have a few shared hosting accounts, but I refuse to give any more money to my current host as they have proven time and time again to be incompetent. (harsh, I know, but there's a long history behind that statement)

Anyway, I do have options, but I have no idea which way to go at the moment. Any thoughts you have would be greatly appreciated.

The primary site is a niche search engine with about 100 to 200 visitors a day, and a database of a few hundred MB which I will aggressively grow once I move to a new account/hardware. I want to make sure I have enough processing power, memory, and whatever else is needed to ensure the database queries are pretty quick. On shared hosting, I have waited 20 or more seconds after hitting the "Search" button to get the results, and that's 20 seconds too long.

I have 2 PE2650 machines at my disposal, 2 procs each (3.2 I think), approx. 10GB memory in each. I thought of running from home on my ISP business account, but I feel I will just be setting myself up for another needed change 6 months to a year down the road.

My other options are VPS hosting and colocation of one of the servers (or both). If I put my server(s) in a datacenter, I will have to manage, which is fine since I have the resources to help, but the machines are only under warranty for another 6 months. They are getting older, but if I could get a couple years out of them, I'd be happy. I could also use one and have the other for parts if needed. If I choose to rent a VPS, I'm really not sure how much memory I would need to keep the database queries returning results fast. Seems like the plans are cheap enough, but offer nothing for memory, so you have to virtually double the price of the plan with add on memory.

I don't have a set price range yet. I wanted to see what everything costs and what I need exactly first before deciding which route to follow. Obviously, the cheaper the better as long as it doesn't compromise performance and/or customer service.

So what I'm really wondering, other than your thoughts on VPS and/or colocation is, how much memory do you think you'd need to run cpanel and a database for a search engine that will probably grow to operate at 5 to 10GB within the next year.