Better aim for higher resolutions?

hi everybody, i didnt really know where to post this but since its quite a general question i guess it doesnt really matter
the thing is that a friend of mine recently told me that nowadays tft screen are getting more coming so there are more people using higher resolutions such as 1280 x 1024 instead of 1024 x 768 or 800 x 600, doing a site that can be seeing well at different resolutions can be quite tricky( either using flash or xhtml ), i usually work for 1024 x 768 or (not that much) for 800 x 600, do u think is better to keep in mind higher resolutions when making a site or ‘normal’ ones? i hope i made myself clear