New Elite -- travel on partner airlines

[pilot]

Sorry ahead of time for n00b questions.

I'll be an "elite" (albeit only Silver Elite) for the first time starting in mid October (or at least so my math indicates). I have three or four business trips that I need to book for earlier in 2009. Here's my question: Are they any important differences regarding potential for upgrade when, as a NW Silver Elite, I book a flight on Continentel or Delta, or my upgrade chances effectively the same (controlling for other issues like type of aircraft, popularity of flight for business travellers, etc). I guess another way of asking my question is that, regarding potential for upgrades especially, and all things being equal, is it better for an NW Elite to book on an NW flight (vs CO or DL), or does it really not matter?