Have a W500 4058CTO 2.3 Ghz Thinkpad with 64 bit Windows OS. Want to upgrade to 8GB ram.
The specs say to install 1066 Ghz SODIMM ram.
Will 1600 Ghz ram operate correctly without causing errors and freezes in the W500?
Will it give a performance improvement over the 1066 Ram?
What brands are best used in the W500?

RAM is adaptable, as far as speeds go; incompatibility (unless you're talking capacity limits) is a 20th-century problem.
Just like cars on a road. You can buy a car that can go up to 1600 km/h, but if the speed limit is 1066, you will only be able to run at 1066.

It won't give any noticeable performance boost either (buying the faster RAM).

Any brand is fine, except perhaps OCZ (they don't make RAM any more, and the stuff they DID make has quality control issues).

Have had previous problems with RAM causing hangups or freezing of system. Some motherboards or systems are more sensitive than others.
Prices for 1066 Mhz and 1600 Mhz similar. If the faster ram will not improve performance then I will buy the 1066 Mhz RAM which is speced to the W500.
Surprised that you say OCZ ram is problematic. Have some in two desktop systems and have had no problems.
Are any specific manufacturers better for tha W500?