I am still very happy with the driver I linked to above, I have had no problems with it last two months, also running windows 7-64 bits.
I would advise to use ccleaner and driversweeper before installing the latest nvidia driver (from their official site, don't take beta) that supports the 570m. First delete old videodriver and other gpu related software in normal mode, then run driversweeper in safe mode and then use ccleaner in normal mode, restart once more and install new driver, restart again and it's done!
My T61p is currently in service depot but I recall the latest nVidia WHQL drivers (258.89 and 260.99) worked really smooth for me.
nVidia has been focusing more on mobile drivers lately and nowadays every major WHQL driver is being released for desktop and mobile platforms simultaneously. There isn't any reason for .ifn modding (laptopvideo2go.com) so that you can install desktop drivers on laptops anymore. I've been pleased with nVidia's WHQL drivers recently.
In conclusion: If you don't depend on certified CAD drivers from Lenovo and would prefer games running a bit smoother, go with the official nVidia drivers.
Also, since 260 series, you no longer need to perform the clean install. The 260 drivers do it fro you: Uninstall the previous driver, reboot and then install the new driver itself.