Are there any open source apps for password management like Roboform in Win 7 or can Roboform be used in 11.04 64 bit? If so how?
There are plenty;
I haven't used GPass and KeePass before, but I have good luck with KWallet (though I'm a KDE user). Chromium has KWallet support and there's a firefox add-on.
I'd recommend reading through their features and picking something that makes sense. KeePass may interest you with its cross platform support, which could allow you to maintain one password system between operating systems.
KeePassX is a free/open-source password manager or safe which helps you to manage your passwords in a secure way. You can put all your passwords in one database, which is locked with one master key or a key-disk. So you only have to remember one single master password or insert the key-disk to unlock the whole database. The databases are encrypted using the algorithms AES or Twofish.