Using Windows 8.1 with a system designed for Windows 7 shouldn't be a problem. Using Windows 7 with a system designed for Windows 8 or 8.1 is where you might run into trouble as there are often no Windows 7 drivers for hardware released after the release of Windows 8. Network adapters and sound hardware are often the biggest issues as Realtek and some other manufacturers don't like having to bother with supporting drivers for older systems when the hardware was designed to be used with a newer OS.
Most your Windows 7 drivers are probably natively supported in Windows 8.1 or have newer 8.1 drivers available from the specific hardware manufacturer or Samsung. It should not be a problem.
It's also noted at the bottom of the page for that unit that:
Using the SW Update function, you can easily download and install Windows 8 device drivers and software.
Drivers page is here:
http://www.samsung.com/ph/support/model/NP270E4V-K03PH
If you find a component that no Windows 8 driver is available for, the Windows 7 drivers sometimes work and in rare cases do not. You just have to try it and see. If you end up with anything that's remarked in device manager, a driver can probably be found manually without much trouble.