OK, some quick thoughts.

1) This is an SBS server running exchange and sharepoint. ie - a BIG single point of failure, if this box dies the business is effectively stopped dead.

2) As such, RAID 0 is absolute [censored] lunacy. Look closely at the other RAID models. Also look closely at the specification of the controller - does that little PERC controller cache the data that is unwritten to disc in event of a power failure?

3) I would suggest some of the midrange HP boxes - DL385 type specification (sorry, I only think in rackmount units!)

4) Think about multiple PSUs as well as RAID

5) UPS?

6) Backup?

7) Stoarge capacity. There's an awful lot of storage-heavy applications there, and if you really want to give them longevity it may be worth considering a seperate storage box, so you can just add more capacity without painful migration.

8) Ask the supplier about the lifetime of the server, how long parts are available for after the model is end of life, etc.

9) Buy the best onsite warranty you can afford - next business day as an absolute minimum.

10) You sure you want to run all that on one box? It might be more expensive, but it will remove the risk of running the whole business on one server. *Then* you can look at cheaper boxes.

This may be a charity, they may feel that budget is tight, but it is never the hardware purchase that is the expensive part of an IT lifecycle. Implementation, maintenance and support will almost always work out more.

I do appreciate your price problem. You might want to have a look on eBay. There's usually quite a few IBM xSeries there at reasonable prices. You'll have to take out a separate maintenance contract with IBM if you follow this route. (Even if you don't want to go with a support contract you'll find that IBM servers are built to a very high standard - a bit like Honda motorcyles.)

A possible alternative would be to buy a couple of cheap no-name servers and run them as a cluster. That way you'll get the good uptime with (possibly) less reliable equipment. A bit like the way RAID works for disks.

Even if you do it at home it's bordering on the insane. I would only run RAID 0 if I/O performance was absolutely critical and the server was part of a cluster. It's enough of a risk to run important stuff on a single disk, but to double (or triple or whatever if you use more than two disks) your chance of a disk failure just doesn't make sense.

Absolutely agree...even my home PC is running RAID1!

Ok, you don't mention how many users this is for and whether you really need SBS Premium as ISA and SQL are not often neccessary, circumstances dependent.

However if this for a relatively sensible number of users (say up to 30 or so), may I suggest you take a look at this:

Hp ML110 G5 - http://www.ebuyer.com/product/140153

The box has space for four SATA drives and is extremely well built for the money. It has on-board raid (its a bit poo, but functional at the price point) and you can sling the enclosed 250gig disk out and put 2 x 500's or larger in for 100 quid (ish). Up it to 4gig memory and you are laughing. We shift perhaps two of these a week, and while we have had one failed PSU, it was more or less DOA and failed while it was being built. Ebuyer sent another and haven't even collected the fautly one yet.

Gig sticks of memory are 20 quid (well that is what we pay for crucial, perhaps a little more to you) and disks are two a penny. It comes with 3yrs ndb on site too, which is a good selling point.

The only things I would consider are:

OOB management card - 100 quid(ish) and possibly a separate raid card (2 channel 3ware or something - about 60 quid) - The on board raid is pig slow at mirroring, but that is really all you can expect at the price. Having said that in a quick rip of the data or power cable from the back of the disks it has never failed to correctly determine the working and out of sync disk when re-mirroring and really might just do for the money.

If you've lots of users, make sure you buy decent 7200rpm disks, with good cache on board.

Hope that helps.