I currently have these programs (Boinc and virtual box) on my main C drive in windows however this drive isnt huge but I have lots of external HD drives and large usb sticks all usb 3.0 standard.

What I would like to do is install and run it from the external drive as I can give it far more storage space to work with instead of filling my main internal hard disk.

How would I go about moving the current installation to the external drive ?

Or

Do I need to re install it fresh and if so how to select the install location?

Uninstall BOINC via Add/Remove Programs.
Move the BOINC Data directory and all its contents from C:\Programdata\BOINC\ to D:\BOINC\ (or whichever letter the external drive has)
Reinstall BOINC.
In the third screen of the installer, click Advanced.
Change the second path from C:\Programdata\BOINC\ to D:\BOINC\
Continue installation.

As for VirtualBox, uninstall it in the same method as above, then reinstall it, tell it to do a custom installation, adjust the path where to install it to D:\VirtualBox\ and continue the installation. (That's a guess, it's been over a year I installed VirtualBox and I am not going to do that now).

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