Kernel source doesn't match kernel?

I am trying Ubuntu Maverick with Trinity 3.5.12, the live image I got from the trinity.pearsoncomputing.net site. I am testing how well it works before I do a potential upgrade. One of my tests includes installing VMWare. I couldn't make it work, VMWare complains that the source in /usr/src/linux-headers-2.6.whatever/include doesn't match the installed/running kernel, so it can't build the required modules. I got the source from the Adept Manager application (plus the build-essential package). Do you folks know anything about that? How can I get a kernel source that will match the running kernel? -- Luciano ES