I have a problem syncing my wallet i'm still running the qt 0.63, wich has a problem syncing to the network. It gains about 1% a day.. bitcoins that have been sent my way cannot yet be seen in my account. is it safe to make a back-up now and uninstall the qt client, and then reinstalling a newer version or a different wallet? Can i just copy-paste my wallet.dat after that?
thanks
You should be able to just upgrade your bitcoin-qt.  Your wallet.dat file can just stay in place.  Back it up just to be safe but you shouldn't have any need to use the backup just because you are upgrading.