I picked up the Steel Series 7G for my setup a few weeks ago and not looked back. I pretty much had the same requirements as you did, I wanted positive mechanical keys that I could tell when they made contact, I wanted solid anti ghosting, and it had to be PS/2 due to hardware boxing.

I am now using the 7G as my everyday keyboard. It’s great for touch typing with its very positive key feedback. The key layout should be second nature to anyone familiar with older style keyboards. The 7G is 100% ghost proof; you could hold down every key on it and it would still output correctly. Whilst there was some complaint in reviews of the arm rest not being padded I have found it's gentle slope to be extremely comfortable, thought I use the IMAK ergoBeads soft fabric keyboard wrist support for a little extra comfort during long game sessions.

I mentioned the key layout before because some reviews picked up on its use of a single key backspace and the oversized enter key (as found on many older keyboards). Personally this hasn’t bothered me as I grew up with this; though some may find it takes a little time to get used to (missing the backspace is common during this learning curve).

For me this keyboard has been worth the outlay, and if price isn’t much of a factor I would encourage you to invest in it. It’s a solid, good feeling keyboard that requires a full key stroke to register a press (so no accidental pressing of keys whilst skimming your fingers over the top of them) and I guess I just feel happier every time I sit down in front of it :P

- Aldercy