But there are more questions you should think about.
Scalability is a real question.
The first versions of Linux were designed for low-end PCs and servers, running on a single Intel Corp. 486 or Pentium microprocessor. All that has changed. Despite its impressive gains in scalability, a single Linux machine can't yet take on the performance of high-end Sun or even Windows servers. Sun's Starfire server, also known as the Enterprise 10000, uses as many as 64 processors. Still, on the low and medium end, Linux keeps up with the big boys.