Choosing an Online Storage or Backup Service

Help me choose a good online storage or backup service, please!

I have two primary machines. An HP dv5t running Windows Vista and a MacBook Pro running OS X Leopard (to be fair, I use my Mac a lot more than my HP lately). Anyway, I backup both machines locally to external hard drives. That seems like a sensible thing to do.

But what happens if a catastrophe happens and the external drives melt down, burn in a fire or get stolen. It seems prudent to have an offsite storage or backup plan.

While this seems obvious, I am having the damnedest time trying to figure out which service to use. Here are my optimal criteria for any service, in order of importance:

1. Mac and PC compatible
2. Secure upload and download transactions (e.g., 128-bit SSL)
3. Secure online storage (e.g., 256-bit AES encryption)
4. Allows encrypted or password-protected files to be uploaded and stored
5. Allowing both archiving and incremental backups
6. Initial X number of GB of free storage; or at the very least a lengthy free trial
7. Ability to choose a personal encryption key or use a service provided one
8. Ability to upload files via a web interface and a desktop client
9. Decent upload speeds (i.e., no throttling before 1 Mbps)
10.   Flexible subscription plans (e.g., discounts for yearly payments, different monthly plans for the amount of storage you need, ability to change plans at will)

I haven’t found a service that meets all of the above requirements, nor do I expect to. However, I am still having trouble choosing one. Below is a list of possibilities. The ones that are struck out I have tried or researched and decided it won’t work for the reason specified. The ones in red are on the verge of being discounted for the reason specified. The others I have not tried yet.

• Mozy (cannot upload encrypted files, especially Mac encrypted disk images)
• Apple MobileMe (uploads to iDisk are not transferred via SSL when using the browser. I am not sure of the protocol when uploading directly from Finder. Relatively expensive per year)
• Microsoft SkyDrive
• iDrive (Looks promising)
• DropBox (Looks promising)
• Carbonite (no Mac client)
• Slicehost (This is my webhost. Is it wise to use a webhost as a backup mechanism, even though you might change hosts down the line??)
• Amazon S3 (Cost prohibitive?)
• iBackup
• ElephantDrive
• Box.Net
• JungleDisk
• <Other???>

Any suggestions? Am I missing some criteria?

I would appreciate the help.