I'm trying to do my first timelapse video and am having problems rendering the video.

I have Lightroom 2.7. In the slideshow module should I be able to export to video? I only have export JPEG or export PDF. Do I need Lightroom 3 or 4 to do this?

I have Photoshop CS4 extended. When I try to find Window -> Workspace -> Motion I can't see 'motion'.
Then when I try to File->Export->Render Video I get the error message 'The procedure entry point CFWriteStreamGetTypeID could not be located in the dynamic link library CoreFoundation.dll After pressing 'ok' a few times I also get error message 'The procedure entry point CFPreferencesGetAPPBooleanValue could not be located in the dynamic link library CoreFoundation.dll
I then am taken to the render video dialogue box, but when I click render I get the error message 'Could not complete the render video command because invalid parameters were sent to a command'

Can anyone help?

I have Lightroom 2.7. In the slideshow module should I be able to export to video? I only have export JPEG or export PDF. Do I need Lightroom 3 or 4 to do this?

You definitely need Lightroom 3 or 4.

Regarding your Photoshop problems: I don't know what ist wrong there, but something definitely is. I suggest you try getting support from adobe regarding this. You might try to re install photoshop...