I dunno how scarse those XP1700's are that overclock that well, but let's not forget the other XP's.
For instance the XP1800, the Tbred B version of that one tends to overclock very nicely too.
I know for a fact, cause I've had mine running 16.5 x 133= 2.2Ghz
I've had it at 2.35Ghz, with 333Mhz fsb.
And recently, since I bought my A7N8X, I've even had it at 2.2Ghz/400Mhz, which is as fast as the XP3200+ supposedly.

Only thing I miss is the extra cache.
I've posted my single channel benchmark, was a very nice score, and I'm getting my new board on saturday, so all will be fine.
Trust me, ya just gotta look at the code, some indicate a downclocked high end Tbred B, like the code AIUCB, that is a high end Tbred B, and if that is on yer cpu, ya can almost bet on it that it'll give ya at least 2Ghz.