I just bought a new system

Thermaltake Armor Jr. Mid Tower ATX case.(Front and rear fans, front intake, rear exhaust)
MSI Neo-F Conroe Ready mainboard
Core 2 Duo E6600 @ 2.4Ghz
OCZ PC6400 800Mhz RAM (2x1gig) "Special Ops Edition"
BFG 7900GT OC
Enermax Noistaker 485W PSU
WD 2500JS SATA Hard drive 8MB Cache (Ordered a second one, its on its ways)

Now, my hard drive seems to be running very very hot usually between 48c and 58c. I thought it might be BIOS, so I updated the BIOS, still the same problem. I get random system reboots during gaming with Oblivion, only happened twice. When viewing the BIOS, or chaning something, then when it reboots, sometimes it won't boot at all, the monitor stays in standby. I have to leave the system off for about 60sec, then turn it on for it to boot correctly. Now...with the side off, touching the HDD, it's not that hot, its only warmish to the touch. BIOS/pcwizard/speedfan, all show my CPU at roughly 42 to 45c, and mainboard chips at 35c. I am frustrated and confused.

Can anyone please please please, shed some light on this?
I'm frustrated and worried about my brand new system.

Thank you in advance. To those that help.