Clean and pristine is probably the best way as it sounds like the curent environment is a bit iffy.
Exchange 2010 can replicate databases and provide instant failover if uptime is really critical - This costs a lot with licences but does not need shared storage.
You can also easily replicate file server data using DFS-R from 2003R2 onwards, again no shared storage required.
Although a SAN does offer a single point of failure they are normally pretty robust, some are really two systems, I recently ran a project on a EMC Clarion SAN and it was built like a tank, everything doubled up, even disk cables - although it was probably over £100k' worth, but many reasonably proced SAN's can have dual power and dual disk controllers so the dingle point of failure is not a fair comment, OK if the building has burned down you SAN is gone, but then so have your two servers.
I have aslo run virtual machines from Windows based I-SCSI solutions, Starwind is very good and the free version allows you to have two concurrent connections - enough for VMWare to provide High Avaiilability and v-Motion.
As to virtualisation VMWare do have some great entry level bundles these days providing up to 3 Host servers + vCentre for a low cost, the ease of management, huge amount of free information on the web, good books etc make it a winner for me.
I have worked (and still work) with both ESX and Hyper-V, as soon as you want features such as Live Migration and High Availability it is much easier on ESX, also licensing Enterprise Edition of 2008R2 which is required for these features and adding in SCVMM makes it as expensive, or more so than the entry level ESX products.
Anyway I think the real issue here is to decide what you actually want or desire and then see what options fit the criteria, I see too many companies that just buy technology but have no idea why they bought product x, or what they intend to do with it.
Get a list of what is vital, highly desireable and nice to have and then compare to solutions and see how much it would cost to obtain each of these.
Although I stated High Availability for Exchange is very expensive, if you could not survive a few hours without E-Mail it may be a bargain, or perhaps a hosted Exchange would work for you? if this is cheaper you could sue the money for two servers and replicate other data and suchlike providing a very resilient network.
Or even introduce stuff in phases to spread cost - but always "Design as a whole" even when implementing in phases, all IT projects are 80% design and planning and 20% implementation - or at least the ones that work well and do what you want them to do are, so think before ordering anything or pressing any buttons!
