"You seemed to suggest if using a PERC raid controller I'm locked into them anyway."
Not at all. SAS disks are enterprise by default. SATA comes in enterprise-class (generally more expensive, but programmed to work in RAID arrays for better performance and reliability) and consumer-class (these are your cheap desktop drives, which are not suitable for enterprise-level RAID arrays). Consumer drives are not rated for 24x7 use, but even if you aren't using them 24x7, their commands are such that you may experience a number of different issues with them, ranging from benign entries in the controller's log to not even being recognized by the controller.
As for actual speed ... I've never really been one for benchmarking for certain speeds, but out of curiosity,
1.5GB file copied in 9 seconds (166MB/s) on the SSD in my workstation;
4.9GB file copied in 60 seconds (82MB/s) on a RAID 10 with four 15K SAS drives on PERC 6;
3.1GB file copied in 59 seconds (52MB/s) on a RAID 10 with four 15K SAS drives under a good load (terminal server) on PERC 6;
1GB file copied in 20 seconds (50MB/s) on a standalone (non-RAID) 15K SAS drive on a SAS 6/iR;
1GB file copied in 30 seconds (33MB/s) on a RAID 1 with 10K SAS drives on a SAS 6/iR;
3.7GB file copied in 110 seconds (33MB/s) on a standalone SATA drive in my workstation;
4.9GB file copied in 20 minutes (4MB/s) on a RAID 1 with SATA drives on a SAS 6/iR (wow is right);
So from this very unscientific survey of the servers convenient to me today, I think 35MB/s should not be hard to attain when using a decent controller (PERC) and enterprise-class disks. If using SAS, two 15K disks in a RAID 1 may be sufficient. If using SATA (which run at 7.2K), you would probably need at least 4, if not 6, in a RAID 10 to sustain those speeds. You said your storage needs are "not that great", so size depends on what you need ... 73GB/15K SAS drives are pretty reasonably priced - 4xRAID10=138GB of usable space to the OS. Of course, this can all depend on the software, the files, and how it is communicated to the controlller that might affect actual speeds.
