Is it better to have Dual Core 2.2GHz or to have Core 2 Duo 1.8 GHz?

What type of dual core are you talking about?

Generally, the Core 2 Duo will be better than the Core Duo or Pentium D as it is much better architecture. But if you're talking about a Pentium Dual Core, then that is the same architecture just with reduced cache and FSB.

1) Core Duo (Yonah)= Core Duo...substantial boost in performance over Pentium D, Much lower heat and power , Intel Core architecture...a very different architecture from Pentium D, primarily used in laptops

2) Core 2 Duo(Merom)= enhanced Yonah....mild boost in performance but at the same price, extension of the Intel core architecture , used for both laptops as well as dekstops

To draw an analogy, the difference between the Netburst (Pentium D ) and Core (Core Duo, Core 2 Duo) is akin to the difference between a PIII and a PIV (altogether different)

The difference between Core Duo/Core 2 Duo is like the difference between say a AMD 64 venice and winchester though larger (enhanced version on the same architecture)

Hope this clarifies the difference

for me i much prefer to use core dou... now.

For performance, I would use Dual core2,2GB.

Unless use on laptop, Core2 Duo1.8 is slower than 2.2, maybe the power consumption is lower.

Hope this helps!
Bill