Well, I'm not much of a hardware guy, but I guess you need to explain a little more beyond that.
Hardware requirements depend heavily on the number of concurrent users you're planning to have, also on the connection type (is this over a lan, on the internet, how much bandwidth will you have?).
Will you have some users uploading data while others will executing read queries or perhaps other update queries?
If you're setting up the hardware to act as an archival machine, where all data is to be uploaded by a single user or connection, then you don't need anything else.
Do you need RAID? well... how important is to have your data safeguarded? If you'll be running a mission-critical real time data server then YES, by all means you need a SCSI-RAID.
Impact? RAID its suppossed to be transparent, specially SCSI.
Maybe a hardware guy could give better insight, but at least you have an opinion.
hope this helps