To get Lion you first need to buy Snow Leopard here: http://store.apple.com/us/product/MC573Z/A
The reason you need Snow Leopard first is that it includes the App Store, which is the only way to buy Lion:
OS X Lion system requirements
To use Lion, make sure your computer has the following:
- An Intel Core 2 Duo, Core i3, Core i5, Core i7, or Xeon processor
- Mac OS X v10.6.6 or later to install via the Mac App Store (v10.6.8 recommended); you can install without Mac OS X v10.6 by using an OS X Lion USB Thumb Drive, available on the Apple Online Store
- 7 GB of available disk space
- 2 GB of RAM
If your Mac does not meet these requirements, you will need to upgrade your Mac before installing Lion. For more information, see OS X Lion - Technical Specifications.
The 2 GB memory requirement is very marginal. Most people recommend a minimum of 4 GB. I can't find an iMac2,1 anywhere but if it's a Core 2 Duo I'm estimating it is a late 2006 model?
Models introduced in 2007 were available with 4 GB and those are the earliest ones I would recommend for Lion. It's a memory-hungry beast.
Hopefully this was more useful than having Apple hang up on you. That's intolerable.
If your computer is too old to run Snow Leopard then you obviously haven't made any investment in Apple hardware or OS updates in recent years. Mac OS X 10.5 went on sale 4.5 years ago with the last free update being released 2.5 years ago.
You can't expect Apple to give you free access to new features and free OS/hardware technical support for years after you last spent any money with them.
MobileMe Support does not provide general Mac hardware and OS Support.
As MobileMe is ending soon (with a years notice and free subscription extensions to the cut off date) the money you paid annually for that does not cover the new iCloud service which is free anyway.