I have a data driven website which is fairly new. I did not use mod_rewrite to make URLs search engine friendly. But fortunately Google already indexed about 500 pages of my website. Now I am considering using mod_rewrite. Should I do this? Will it effect to my indexed pages? Thanks,
Search engines can crawl urls with query strings without a problem. The (small) advantage of mod rewrite is that you can get keywords in the url.