Tech Report has put together a 18 page round up of CPUs from yesterday and today.  The comparison is nice as it includes OLD hardware to give you a real feel for what kind of speed bump a new desktop would actually give in the real world.

The real gold however is in a single page: the value proposition:

With the data plotted [overall performance per dollar], we can see a few other contenders that might join the Athlon II X3 and X4 processors as value stand-outs at higher performance levels, including the Core i5-750, Phenom II X4 965, Core i7-920, and even the Core i7-960.  The ghosts of the P4 670 and the Core 2 Quad Q6600 haunt our value scatter plot, as well, reminding us of the dismal CPU values in days past…

The inclusion of total system prices alters the complexion of our scatter plot somewhat, too, mainly by making the LGA775 and LGA1366 processors look less attractive. The cheaper chips lose their luster, as well. The Core i5-750 and i7-870 remain nicely positioned, while the poorer values include the Core 2 Duo E8600, the Q9400, and the Core i5-661.

Tech Report even goes on to include the various electrical costs of the difference chip & system power draws which further extends the Intel lead and creates a clear cut winner.  Ok a few winners:

• To build a reasonably beefy machine for around $700 and what the maximum bang for your buck – get the Core i5-750.
• For more performance without breaking the bank ($1000-1200) pick up an entry level i7 – either the i7-920 or the i7-870 (the high end cores are much more expensive but only marginally faster)
• For more efficient, always-on systems such as a HTPC consider the core i3-530 which will be easier on your electric bill and quieter than the i5

I personally invested in a i7-920 machine this summer (overclocked at 3.21Ghz with stock cooling) and love it.  I can encode a 90min movie from DVD insertion to finished file in ~16 minutes.  In fact, the two most significant performance improvements I have seen in a quite while in my own usage are my i7 core and my more recent SSD upgrade on my boot/programs drive.