Snow Leopard wants me to buy iWork?

I updated my iMac with Snow Leopard a little while back (2-3 months) and now I am being prompted to buy iWork as it tells me my trial period is over? What is going on? When I upgraded why did I lose the following:
Word, Excel, Power-Point , etc?
I was told my iMac was the first to have the Intel Chip, bought right before new aluminum iMacs came out.

Model: iMac 5,1
Processor: 2.16 GHz Intel Core 2 Duo
Memory: 1 GB 667 MHz DDR2 SDRAM
1 processor, 2 cores

Thanks for any help.