Which Upgrades Are Critical for 27" iMac???

I have decided to pull the trigger on a 27" iMac. I am torn over which upgrades to get though. I'll be honest, my wife and I don't have a lot of extra wiggle room in the pocketbooks for upgrades, but we aren't completely strapped for cash (obviously if we are getting a ~$2000 computer). We plan on using it as our primary computer for at least 5 years. We don't want to get something that will be way behind in 2-3, but also don't need the best. I will use it for general web browsing. My wife is the one who will really use it the most. She is an amateur photographer, will be using photoshop and different editing software.

What do you all recommend? Is the 3.2 GHz really worth $200 over the 2.9GHz? What about the other upgrades? I hear the fusion drive storage will really increase performance.

My wife is a teacher so we will be getting the Education discount ($100 off). We are willing to spend up to $2000, could I get some recommendations on the best upgrades to stick under the $2000 price point? If it really isn't necessary to make any upgrades for our plans of usage, please recommend that.

Thanks!

Personally, unless you're gaming or running really intensive apps (like the Adobe CS apps) regularly, I would stick to the base model and save your money. You can easily upgrade the memory and storage options yourself down the road if you find the need to do so. In my opinion, the "Fusion" drive is more of a gimmick than anything else. I'd sooner go with a straight SSD and add mass storage externally if you find it necessary. (EDIT: I had a look at the storage options, I didn't realize that the only pure SSD option was $1300. Given that fact, the 1TB Fusion drive option IS probably your best option for a cost-effective factory upgrade)

What you can't upgrade (easily) are the CPU and GPU options. Clock speed differences (i.e. the 300MHz difference between the 3.2 and 2.9) are going to be negligible in terms of real world performance. The only time you'd see a significant difference is when you change architectures (i.e. Core 2 Duo vs. Core i3 vs. i5 vs. i7). So, if you're going to purchase a factory upgrade, those would be the areas I'd look to address. But again, for the needs of the general user, the base model is probably WAY overkill.