Infrastructure Software

I was wondering about Oracle Solaris and Oracle Linux. How do the two compare and what arguments speak for one or the other. I found several articles in Google that suggest that Oracle sees more potential for Solaris in the high-end server business and that it was still a long time for Linux to catch up. Similar to HP, which offers both Linux and Unix to its users, while it is positioning Unix specifically for the high-end mission-critical deployments.

For instance: http://www.serverwatch.com/news/article.php/3861376/Whats-the-Future-of-Linux-and-Solaris-at-Oracle.htm

The article and others alike do not really mention anything about the computer platform. It might compare Solaris on Ultra SPARC 64-bit RISC technology, which sure has its advantages, with Intel x86_64 running Linux. But how does Oracle Linux and Solaris perform when both running Oracle database on the same x86_64 platform? Support for the 64-bit extension and CPU enhancements on the x86 platform were introduced as of Open Solaris 10. The download of Solaris 11 Express from OTN only mentions x86 though. I can imagine it makes sense to run Solaris on x86 hardware in case you already have a Solaris infrastructure or have specific Solaris requirements, otherwise I guess Oracle Linux will be a more economic option. I wonder if this assumption is correct?

I also wonder whether or not the x86_64 CPU architecture, which is actually still CISC based from what I understand, is really a good choice, now since the the Desktop and PC server market finally decided to arrive in the 64-bit world.

Any thoughts?