If you've old but important software that no longer runs under Windows 7, then you could try using XP Mode, a virtual copy of XP that runs in a window on your Windows 7 desktop. But there's a big potential problem, as XP Mode only works with systems that have hardware virtualisation (AMD-V or Intel VT) built-in and turned on. If you've a compatible CPU then this may just be a matter of enabling the option in your BIOS set-up program, however some high profile brands, including Sony Vaio, disable the setting for "security reasons". And that blocks XP Mode from working, too.
One solution has emerged, but it's a little risky, as essentially you'll have to alter a byte in your laptop firmware and hope this doesn't have any unexpected side-effects. Gulp. If you're feeling brave then take a look at theFeature Enable Blog for the details, but don't blame us if it goes wrong.
A safer approach might be to use VirtualBox, a virtualisation tool that doesn't insist on hardware support, but then you will need to find a licensed copy of XP (or whatever other Windows version your software requires) for its virtual machine.