I need to present the user with a matrix of which one column is editable. What is the most appropriate control to use?
I can't use a ListView because you can only edit the first column (the label) and that's no good to me.
Is the DataGridView the way to go, or are there third party alternative components that do a better job?
DataGridView is the best choice as it is free and comes with .NET WinForms 2.0. You can define editable columns or read-only. Plus you can customize the appearance if required.
DataGridView is good.
If you prefer a prettier interface, Telerik controls are better.
If DataGridView will handle your needs, it's the right answer. Another option (although it seems to be unpopular around these parts!) is Infragistics NetAdvantage. The downsides to Infragistics are primarily a high cost and somewhat steep learning curve; the upsides are that these are some of the most powerful controls you'll ever find -- so if you need their flexibility, go for it.
I don't have experience with Telerik (which has been mentioned by others here), but they do seem quite good. Being that my company has invested fairly heavily in Infragistics, we're not liable to switch any time soon ...