Chances are the technology in your industry has evolved since you first acquired your IT equipment. And your competitors are aware of this and are probably implementing the newer technology. Nobody wants to be left behind, however making the right choice can be a difficult and drawn out decision.

Here is an excerpt from entrepreneur.com:
http://www.entrepreneur.com/article/159576

Are you or your employees spending more time trying to accomplish tasks?
For instance, does it seem to take longer to launch applications on a given PC? Has the network grown sluggish at handling routine traffic? If so, it’s probably time to consider upgrading.

Is your business using powerful new applications?
If you’re planning to install processor- and memory-intensive programs, it’s likely your PCs will need to be upgraded. Digital video editing, for example, is extremely processor- and memory-intensive, and requires a large, fast hard drive for storage.

Have you added, or are you planning to add, more users to your network?
If so, it might be time to consider upgrading the storage capacity and/or memory of your shared office server, or upgrading other network-related equipment.