Dual core with 2GB ram can't perform well on Windows 7. To make your old laptop to work like a latest laptop, install a Linux OS on it. Recommended Linux distro for an old Windows 7 laptop is Linux Mint XFCE. Your dual core laptop with 2 GB ram will work like an i7 laptop after installing Linux Mint Xfce. It is almost like windows and can do much more things than in Windows. You don't need an antivirus too other than the built in firewall in Linux Mint.