PSU strong enough?

Hi, I just bought a few new parts. (Motherboard, Memory, CPU and gaming case)

My pc randomly reboots (not often, but still not cool..). My starcraft2 often freezes on loading screens or sometimes in game. I have a solid 100 FPS ingame and all my temps are at + - 35.

So I have a Intel 2.6k 3.4ghz core i7 sandy bridge proccesor.
8 gig 1300mhz 'some name brand' memory.
dark knight 4870 ati as graphics.
Some oem (dunno what that means) Strawberry mountain motherboard.

My power supply however is only 450watt. 500 max. (Aopen)
Is that the cause of my random reboots / starcraft 2 freezing? Is my psu too weak?

I JUST bought the new parts, so simply buying a new stronger PSU for MAYBE fixing something is out of the question. Can any of you OC junkies tell me if I have the power?

btw my pc is not overclocked.

OEM means Original Equipment Manfacture. When you buy an OEM part, you just get the listed product, no accessories. I.E. OEM CPU only comes with the CPU, not the heatsink fan. You probably should upgrade to a 550 watt.

Can the random reboots damage my pc?

imo, you're running quite borderline for that hardware configuration. simply put, yes. you can corrupt you're OS that way