Oh, a bit of a side note on hosting for startups. I know many people want to save costs by centralizing hosting, but as a word of advice keep your database, mail, and web servers separated. By not doing so you've created a single point of failure. Not only that, but it makes securing things appropriately more difficult (ie. you are unable to create only web server specific firewall rules for the server).
A good trick we've been using while building http://www.webpop.com has been to use the cheap small instances on the Rackspace cloud to build a mini version of a nice distributed setup with load balancers, web servers, database servers, monitoring, etc...
The small instances are very cheap, and we've been automating everything with chef, so it's east for us to gradually scale up by adding large instances to our cluster instead of small ones.
This means we've been able to build a scalable and secure infrastructure, that didn't cost us much more than a hundred bucks a month during development.
We've been doing the same thing on Linode, and initially did our development on Rackspace cloud. One important thing to note about Rackspace cloud is that your private network bandwidth is limited to 10mbps when you're on their small Xen instances - this may not be a big deal during development, but after you go live if you have any traction, then with simultaneous backups, sql replication, and any other chatter that might be happening between servers, it can really "slow down", and you might end up having to move to larger instances simply for the port speed, even though your existing server is sufficient in regards to CPU, RAM and disk.
Our testing ended up leading us back to Linode, since with a simple support ticket you can up your private interface to the full 100mbps. So our "combo" ended up being Linode + Amazon S3 (since for many of our items the reduced redundancy storage is sufficient, and is half the price of could files).
It's sure fun though setting up your own small "cloud" system ;)
