I learned HTML/CSS from the nettuts 30 days guide. I created my landing page from scratch, it showed up fine in chrome, FF, IE9+8 but it's completely messed up on ie7. From looking at recent data it seems that only 2% of internet users use IE7 as their browser.
It seems that IE7 doesn't like some CSS, I really don't want to waste my time learning what doesn't work in IE7 since it is being phased out. Am I just being lazy here & should fix my LP to accommodate IE7 users? Or not worth it?
Depending on the offer, significantly more than 2% of your conversions could come from IE7. I have a campaign running right now that performed like this on facebook in Australia after ~5k clicks:
IE: CTR - 0.235% CVR 8%
FF: CTR - 0.095% CVR - 5.4%
Chrome: CTR - 0.148% CVR - 4.1%
Safari: CTR - 0.039% CVR - 0%
Food for thought.
Personally I wouldn't worry about it. Very few people use IE7 because of the forced upgrade to IE8. My guess is that the only reason people haven't upgraded is because they aren't allowed to (computer at work). And people at work probably aren't going to be converting for you anyway. If you are worried about it you can try and drop in something like this: http://code.google.com/p/ie7-js/ and maybe that will fix it without any more work on your part.
I wouldn't waste time catering to the 2%. Have some analytics like Clicky running on your lander and if you find a significant % using IE7 or some anomalous CTR results with IE/IE7 then think about optimising the CSS to suit. Otherwise just test your page in FF/Chrome/IE or use browsershots, if she loads OK in the latest various browsers then go for gold.