I would look at a system that runs SATA drives, SATA is a lot easier to find. You will want to look at the specs on the drives you purchase to see what the manufacturer states the sustained write speed is. I can't say for sure on running XP on our servers. There are a couple of our lower end servers that are converted workstations. They have been validated for client operating systems, but most of our servers are not tested to work with any client OS. In theory you should be able to install XP on any system validated for server 2003, but there are subtle differences between the two OSs so you might have some issues. You can find some really cheap 2950s for sale and in my opinion the 9th generation servers were one of the best lines we have ever come out with. You will see a noticeable performance difference between 9th gen servers and older servers. The tower version(2900) runs quieter and is a better choice to be used in a home if noise will be an issue. The 2900 tends to be more expensive because used tower servers are more sought after for home use. Any rack server that is older than 10th generation is going to be very loud. 10th generation saw improvements with fan noise, and it has gotten continually better with later generations. If you are able to put the server/s in a garage or some room at the other end of your house then it shouldn't be an issue, but you likely won't be able to sleep or watch TV in the same room as a rack server. They are tolerable at idle fan speeds, but if the CPUs are highly utilized then the fans will max RPM and become extremely loud. One other thing to consider is that you may be better off with a workstation or desktop computer. Is there a specific reason you are selecting a server to perform this video streaming function?
My plan for this Poweredge 1750 is not so much for use as a server as for capturing an uncompressed video stream. I will need to obtain something around 35Mbit/sec write speed to the internal SCSI drives. Is this doable using what comes with the factory machine or am I asking too much? Any suggestions as to how to set up the raid for my application will be appreciated.  Thanks!
PowerEdge 1750: setting up the raid 