Well, you can hire a London black cab through a number of apps such as Get which will give you a fixed price.

That fixed price gives you the following major benefits in my view:

- interesting badinage with an individual with honed irony
- interesting navigational debates with an individual with an enlarged hippocampus (http://news.bbc.co.uk/1/hi/677048.stm)
- a ride with someone who is highly trained to drive you safely to your destination
- knowing that in most cases you are paying an individual for their efforts

What you get with Uber:

- convenience and low cost
- often indifferent driving
- routes by Google
- a competition crushing price whose losses are subsidized by venture capital
- a sense of regret when you pay for a trip that the driver, you and the competition are being shafted

My company has been working with Postgres for 5 years. We've built several large sites with it for others and run a webapp for hospital professionals backed by Postgres (with a fair amount of use of stored procedures). Not only have we found that Postgres has been incredibly stable over the years, but we have also found that upgradeability an enormous boon. The incredibly smooth upgrade process between major versions have allowed us to seamlessly move between versions. Also, the excellent release notes allow us to easily pick up any changes that are likely to affect our systems. Postgresql is both a wonderful product and an excellent community.

You can use heartbeat + Xen over 2 boxes to get HA, so long as you have shared storage. There are some notes about how we did Xen live migration on our "perspex box" in my comment here: http://ask.slashdot.org/comments.pl?sid=1171301&cid=27295879 Citrix Xenserver now offers "Live Motion" for free: http://www.citrix.com/English/ps2/products/feature.asp?contentID=1686939

We had a lot of fun making a perspex case for two DG945FC boards with E6300 processors, with a third board to act as the controller. See http://campbell-lange.net/company/forums/february2009/ We put the machines together in a case in order to demonstrate both services and operating systems migrating between machines. Windows 7 moved across well. Xen works well on these. VMWare Infrastructure however doesn't support the boards. As the previous poster mentioned, memory is all important. We've found this little test rig is hugely useful for testing, particularly when one has to throw up different Windows instances to check Linux interoperability.