That's primarily up to you.
You can install the two toolsets side-by-side, and they won't interfere with each other. The plus side is that it can make it easier to transition from one version to the next. The downside is that it takes up more space on your hard drive. It's important to note, however, that you're not "overwriting" a previous version when you install a newer one.
If you plan on removing the old version, whether now or at a later point, it should not impact the new version. Some of our older versions of NetAdvantage for .NET (I think as recent as some time in 2006) removed some "common" files when uninstalled, but to my knowledge this is no longer the case. Even then, at worst you can simply reinstall the newer version to replace those common files.
Other people may have other advice that may help you make a decision.
Vince McDonald
Manager of Developer Support, MCP
Infragistics, Inc.
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