How Nehalem based PCs perform on single thread applications?

I am trying to decide whether to buy a new powerful workstation now or wait for the Nehalem based PC. I heard that Nehalem based PCs will be at least 30-40% faster than the current fastest Penryn based PCs. Is that on running applications that support multi-core/multi-thread? How does a Nehalem perform in terms of single thread applications running Windows Vista Ultimate 64-bit?

Here this may help.
http://www.breakitdownblog.com/int [...] increases/

The true answer is:
Unknown.
It depends.

I am guessing based on some very early leaked tests that it will be 20% faster than current 45nm parts on a clock for clock basis. That puts the entry level 2.66 cpu in the E8500/E8600 class for single threaded applications.

If your application will use lots of the new instructions, then it may be very much faster.
For multi core capable programs, it will be much faster because of hyperthreading giving the appearance of 8 cores.

I am also guessing that it can overclock to the same levels as current cpu's based on it's use of the same 45nm manufacturing technology.

Gigabyte's X58 prototype enthusiast motherboard has features removed that an overclocker would not want... So they say. If true, they must have overclocking capability.