I have all my books in Calibre... then I have my calibre library in my Dropbox folder.
Dropbox is a sync service that you can install on one or more computers. It keeps copies of everything on multiple computers and one copy on their cloud servers. It is automatic and instant. You don't have to do anything but keep drop box running. Whenever something changes it will get synced with that cloud and other PCs almost instantly.
Dropbox gives you 2GB for free... You can get more (up to 3GB) for free by having others sign up using your referral ID. Or, you can pay a fee to get more space. Your 1GB library would fit fine into the free space.
Just today I d/l'ed 26 recent Kindle purchases, liberated them and put them into calibre. Within a few minutes they were all safely in my dropbox.
If you decide to get a dropbox, I would appreciate it if you use my referral link:
https://www.dropbox.com/referrals/NTMwMDU2MDk
Once you get bigger than the free dropbox you could pay... but it isn't as cost effective as some other services.
Jungle Disk is software that you pay a monthly fee for the software plus you pay $.15 per GB per month stored on their servers. $ wise this is the most cost effective storage for medium size ... perhaps up to 10-30Gb or so.
Then if you get really big you would move to something like Crash Plan... which gives you unlimited storage for less than $4 a month if you pay for 3 years up front. If you have multiple-Pcs you can back them up with the family plan for $5 a month if you pre-pay for 3 years.
The above is my progression plan. I also back up using Time Machine locally.. the cloud stuff is just emergency... plus the ability to access stuff from any Internet connected PC is a bonus.
BOb