Please feel free to ignore everyone who is expressing their regrets on your behalf that a new model will be available in early 2009. These people generally fall into two categories: those who have money to burn and love to buy the newest hardware at each release, and those who never buy anything because they are always afraid the next iteration will be better.
I have a 20" aluminum iMac I bought about 9 months ago when switching. It's quick, runs all the software I need, has never had virus, malware, crashing, BSOD, or other common MS problems, and I love it. And another reason people love Apple is that your iMac should last you several years if you take care of it--lots of people on these forums still run G4s without any problems.
Congratulations--I hope you enjoy your iMac for many years to come.