Start off id like to call myself not a noob but Id probably be lying. What does this error look like what does it say on the bsod.

It's called the Memory Parity Error-BSoD, and is thrown when 2 or more Bits in an Byte are detected as wrong. ECC just helps if 1 Bit in an Byte is wrong, which then can be corrected by the ECC.

We have this error a lot with on our HP xw4x00 Workstations.

The positive thing is, if you get a Memory Parity Error BSoD, you definitely know that a DIMM is defective.

Well, BSODs have nothing to do with non-ECC memory. Even when NOT overclocking, anyone should stress test RAM/IMC subsystem for at least 36 hours at a temperature at least 10 deg C higher than what will normally be the highest stress temperature(i.e. slowing down fans etc).
I stress test my RAM/IMC for 1 week using Prime95 x64 with custom settings and then 1 more week using Lynx. Reliable stress testing can only be done under x64 OSes.
Having RAM/IMC stable, CPU stable and ICH/IOH stable and THEN reinstalling OS with proper device drivers, I can assure you that you will never see a BSOD again nor any strange behaviour from your rig. Thus, no need for ECC RAM. If a clean OS install with proper device drivers BSODs, it is obviously because the rig is non-stable and not because of non-ECC RAM.

The Core i7 doesn't support ECC memory.

I wonder if those DDR3 manufacturers come up with some nice ECC and registered versions. /me likes the stability with the speed of those of their DDR2 predecessors. According to m$ research a lot of those pesky BSODS are caused by the use of nonECC/regged memory sticks.

We clearly state these are high end memories, and yes they probably don't matter much to the mainstream user, who may still use Core 2 Duo & DDR2 and be content with it. There are apps where it matters, and there are those where it doesn't. Do remember that caches are not panacea for everything, else Intel & AMD wouldn't bother with speeding up the main menory access. Simply whoever spends $2K on a 975XE, board, casing and PSU for it will probably not mind spending a bit more for maxx-out memory for it too

Whenever I see those kinda test, I can't help but wonder if there is any real-world benefit.

Apart from bragging right and e-peen, does high-end memory actually improve system performance noticably ? With today's huge L1, L2 and L3 caches, I have strong doubts. The fact that most of these advertiser-pleasing tests are done without any reference to a non-elite RAM config strengthens these doubts.