In the past I was under the impression that OCing with the FSB untill the ram became unstable then working with voltage and the multiplier was the way to go, but I noticed on the 5000+ BE review done on this website only the multiplier was used. Which is the correct way to proceed? I am OCing a 5400+ BE

Either way is the correct way. It is typically easier to adjust your multiplier than the FSB...but either is doable.

But wouldnt more gains be seen by OCing with the FSB? since this is ocing more than the processor?

That's a common misconception by veteran OCers. I know for sure games wouldn't be impacted, but dunno about other memory heavy programs such as photoshop.

So are you saying that upping the multiplier also OCs ram or that there is little to no gain by OCing the ram?

Upping the CPU multiplier does not increase the ram frequency since the FSB is untouched. Even if you do increase the FSB and ram instead of the multiplier, the gains will be minimal compared to just increasing the multiplier, but it's your choice.

Since the above posts are somewhat confusing, I'll try to clarify. 90% or more of the performance of the CPU is determined by the final core clock. That can be increased by either increasing the base clock (often FSB on Intel systems) or by increasing the multiplier, or both. Increasing the base clock has the advantage that I/O speeds (including RAM or FSB) are also boosted, and the disadvantage that OCing more of the system increases the chance of encountering a problem.
Since historically core clocks have significantly outpaced I/O, current CPUs are designed with big caches to minimize the effects of relatively slow I/O. Thus boosting the RAM or FSB speed doesn't usually help a lot, but it might give you an extra 10%, everything else being equal (which it often isn't!).