I was using the official Bitcoin client some time ago. It was version 0.5 I think. Then my computer crashed and didn't use Bitcoin for a long time.
I was lucky because I had a backup of the wallet. Today, I installed the latest version and it's different. It is running for many hours now but it's still at 18-20 %.
Should I leave it as it is or I can turn off my PC and continue tomorrow?
If I use my old wallet, will it start from the begining? If yes, is it better to stop the software, delete everything, replace wallet and start all over again?
bootstrap.dat
is no longer necessary due to changes in the client.