I bought the Witcher 2, and I really like the game, but I'm so frustrated! I have a fairly high end gaming laptop with a Nvidia GT540M and a 2.4 ghz quad core processor, I have the latest version of the game (DRM free) but I'm getting about 20 FPS on LOW setting! I've tried many different setting combinations and downloaded the latest driver. Nothing helps! Please help me!
Make sure that your GT 540m is actually enabled. It could be that the game is still running on the Intel integrated graphics. There may be a switch on your laptop, or you may have to go into your power settings to tell the 540m to turn on when gaming, and not use the integrated graphics.
Secondly, the 540m isn't a powerful GPU, it is about equal to really old video cards like the 7900GT, or Radeon X1950 Pro, which technically fall below Witcher 2's minimum system requirements. Your laptop is not high end, it is an entry level gaming laptop at best.
Witcher 2 calls for an 8800GT 512MB or Radeon HD 3850 512 MB as a minimum video card. The 540m is several tiers below those cards. If your 540m is running, it just might not have the grunt necessary to run Witcher 2 well. It is a very demanding game, you need to have a pretty high end laptop graphics card to run it well. Probably something like the GT 555m at minimum.
Like supernova said, your laptop is not a high end one.
Plus, I'm not too surprised about this. The GT540M is just an entry level mobile gaming card, that would play some of the older games at good settings and resolution, but not demanding games like Crysis, Metro 2033 or The Witcher 2.
Most cards struggle to run the Withcer 2 at it's max settings, so it isn't really surprising that you can't stay above 20 FPS on low.
Also, at what resolution are you playing the game at? If it's at your laptop's native res, I'd advice you go down a little more.