I had this discussion the other day with a few muslims actually. Capitalism isn't any better or worse (per say, there are worse systems) before you add corruption into the equation. Generally, any government eventually is going to need to lower classes to rise up and kick out the tyrants - having a governmental system that doesn't inevitably eventually become corrupt through "old money" is an impossibility.

Aside from zakat, which would be good socialism, there is a book "Dajjal - The Antichrist" that addresses this question, although it is written by a sunni muslim, they tend to keep it mostly on the Quran side, and they don't approve of things like stoning etc so I thought it was a good read. In this book the author basically establishes that a "true" muslim empire would be capitalist-ish.

"Pure" socialism is not fair as it redistributes too much wealth to the lazy and unproductive, whereas modern corrupt capitalism doesn't care if you starve to death (capitalism without corruption and with socialist programs like zakat to support the poor would be ideal imo.)