**SOLVED** (thanks) Advice on "Microsoft Visual C++" error please :-)

I would hazard a guess that it's OK to proceed, since your newer version of the Visual C++ Redistributable should be compatible. It's telling you that you already have 2010 C++ installed (it probably got updated with a Windows Update at some point). 

That is a redistributable program. If you did not have it, you would need to install it to install the main program you want to install. Since you already have a newer version of it on your computer but that program is looking for a specific version and they should not have programmed it that way, but since they have, you can either look up at Microsoft what it asks for by going to the Microsoft Visual Studio website like it states in the bottom or just go to Microsoft and "Search" for The Visual C++ 2010 x64 Redistributable Setup program to install. Computer games are the same way: One game might have used the 2005 Redistributable Package (which may be included with the game since those are smaller) while the next one uses the 2008 Redistributable Package program. Both are installed on the computer and both are needed because the game software (with two of those with different needs) need those to work. Just do a Search at Microsoft or click the link down at the bottom of the page for the Microsoft Visual Studio website, find the Redistributable program and install it.

The end result is that different years of different versions for the same program are needed, because - Microsoft did not program the next version (2010 vs. 2008 version) the same way as the old program so they are not compatible with one another and both have to be installed to make perhaps two different other programs work correctly on the computer and both versions would have to be installed. Babbled enough, I think you get the idea.