Can iWork 06 and iWork 08 coexist?

Yes, they co-existed fine for me - the new ones go in "iWork '08" instead of "iWork '06". I only used Pages, though. One thing to remember is that if you save anything in 08 during the trial, it won't open again in 06, so keep a copy in 06 if you decide not to go with 08 after the trial.

The packrat that I am, I've got all three versions on my drive. Adding to the above, you'd need to explicitly save the iWork '08 document to the earlier version if you decided not to buy it after 30 days.

If you can switch across though, I would. iWork 08 takes considerably less space than iWork 06 did.

iWork 08 - 688MB - Three Applications
iWork 06 - ~2GB - Two Applications, (non-universal)

does anyone know where i can download iwork 06? i bought it online last year and still have the key. but my imac came preinstalled with 08.

thanks.