For the VHS tapes, you'll need to find a new videoplayer - one that will replay NTSC (i.e. US format) on a PAL/SECAM television. Those used to be the "high-end" tape players, but these days they are pretty common over here. (Or, you can always bring a small US NTSC tv with you along with your current tape player. But the tv will work only with the tapes.)

For the DVDs - bring them along. It is possible to get a "de-coded" or sometimes no-code DVD player over here. (Generally the cheapest DVD players here are the most likely to be no-code machines.) And even if not, you can always play the DVDs on a computer. Most DVD programs require you to select the Zone you want - 1 is the US, 2 is Europe (and there are others) - and won't allow you to change more than a set number of times (3 to 7).

To get around that, just load a second DVD program onto your computer - leave the first one set up for Zone 1, and set the other one to Zone 2. That way you can keep all your DVDs handy for watching.