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.
It is likely to be because your computer is slow validating the blockchain but not necessarily. This answer may help you.
No need to move your
wallet.dat, just safely exit bitcoin-qt and make a backup copy. Then upgrade your Bitcoin Core install. Always use the official release version which you can get from www.bitcoin.org. It will automatically upgrade your wallet file if there are changes to that format also.