http://www.google.com/apps/intl/en-GB/business/index.html

This might be useful for you.

The first question is why do you think you need it?

Could based computing is nothing new... in a way SCOLinux users and other Dumb terminal users were using a subset of this technology over 20 years ago.

The cloud can be used for:

1. Storage
2. Processing
3. Hosting
4. Replacement desktop
5. Online gaming

and can negate the need for a simple backup strategy (if the cloud supports backups, as many of them do). There's an inherent strength in the cloud too, with multiple failover devices meaning that if a Server goes pop, another one simply takes over with no downtime, all the data is migrated and shared accordingly and nothing is lost. As a cloud consumer you're also not aware that a server even went pop on large installations.

You'll still need a PC/internet connected device to use the Cloud, but you might not need a Quad Core, hyperthreaded monster running at 1000 Watts. In fact a very modest PC with a basic ATOM based processor will easily suffice as much of the processing work can then be carried out by the "cloud" again depending on what you'd like it to do for you.

In a way you're also being more green. Purchasing a low powered PC and allowing the cloud to process/store stuff for you is more efficient. Your PC for the most part is idle but still munching anything between 20-1000watts. The cloud computers are designed to spread the workload around meaning that they're not typically idling for any length of time. They're typically also not stressed overly as good cloud based solutions monitor load and draft in new PCs to take up the load as it expands.

Google own Google Docs is a useful replacement for Microsoft Office, although not as feature rich, it does offer many features AND your documents are stored "safely" with Google online, meaning you can access them from anywhere. Another good example might be Zimbra.

We did a quote recently for 80Terabytes of online storage on a cloud based network and the cost was acceptable compared to the outlay of purchasing the same amount of storage inhouse.

The cloud has many uses and its not just a question of "should I use the cloud?". Quantify your question by letting us know what you would like to do and the users here I'm sure could offer up some suggestions to your specific requirements.