A couple of observations:
A- You ought to be talking to a server specialist at HP / a large HP partner about this.
B- In general,
SSDs get somewhat faster in larger sizes, and
SSDs have orders of magnitude more IOPS than mechanical HDDs,
... so for these reasons, today it often makes less sense to separate out TempDB, SQL logs, pagefile etc on multiple volumes. Just put it all on one large, sufficiently fast volume, backed by HDD or SSD as needed.
Or if you must separate, do so by cost of storage media, i.e. boot OS, apps, pagefile go on mechanical HDD, database files go on SSD.
C- Lots of people use OS -> RAID controller -> SAS/SATA SSD. While this is a completely valid choice, it contains quite a lot of duplication of effort. I.e. the RAID controller emulates being a linear block device towards the OS even though it isn't; the SSD emulate being linear block device towards the RAID controller even though it isn't.
Instead, investigate using just one high-uptime PCI-Express based SSD for the same workload.
D- You're getting the expensive HP server which supports 4 CPU sockets in 2U. Would 2 sockets in 2U be enough?
As a rough sketch, I would personally think along the lines of:
A 2U, 2-socket Intel Ivy Bridge or upcoming Haswell class system
For OS, pagefile and those ARCServe replication files either a: one 4-disk enterprise SAS mechanical HDD, BBU'ed, write-cached RAID 10 array of sufficient size and speed, or b: one or more read-focused, large, JBOD'ed SAS/SATA SSDs. (Choice depending on what the vendor is selling, pricing, and uptime needs.)
For the database files, one highly reliable PCI-Express SSD (a.k.a. IO Accelerator) such as LSI WarpDrive, Micron Px20, Fusion-IO, etc.