I saw some posts here having a similar topic, but I haven't quite found what I am looking for.

All I need to do is transfer my Windows 7 (Professional, 64bit) which is installed on an internal disk on my Dell Latitude laptop to an external USB disk in order to have my original system available for booting while installing a new system on the internal disk, which is essential since I need a working project environment for work in case the new system takes some days until fully completed.

I already tried a disk clone with Acronis and Clonezilla, but in the 1st case it didn't even booted the clone and in the 2nd case it booted, but stopped with a bluescreen (and rebooted too fast to be able to see any error code).

So has someone done successfully what I am trying to do and can help me out here?