I work at a small office and we're overhauling our network setup there. We're a web dev company and at the moment we have 50+ production sites running on the same machine that runs our internal email, which is just plain stupid. We're moving all our client hosting off site and are now looking for something to run our internal office requirement. Below is a brain dump:

• Equal amount of Mac & PC, about 25 machines in total.
• We need a central "server" to host files that should be accessible everyone as a "network drive". If possible we'd like to use low cost hardware for this (Mac or Win based). Disk space should be upward of 1TB.
• Ideally we should also be able to run a small web server on this machine (LAMP stack) to run some planning and billing applications we wrote ourselves.
• We need some sort of MS Exchange alternative for things like a shared calendar and especially being able to set Out of Office replies.
• We have one printer that is connected to the network
• Setup should be something can preferably be managed easily via a graphical interface and NOT require command line skills.
• Users want to keep using Apple Mail or MS Outlook

After a quick google I came across the Zimbra collaboration suite, can anyone recommend this or any other solution for our office?