As mad4 mentioned, tables by themselves won't be a problem. Some people argue that sites will get better search result if less HTML code is used in the page. Tables require a lot more HTML code than using CSS. So you can make some correlation based on these facts. For me, I don't see a difference in search results between sites made with pure CSS and sites using tons of tables.
I agree. I always use tables in my sites and never had a problem with getting indexed. If you ask me I think tables are better, they are very easy to use.
I agree with the statement that search engines have not problem in indexing page with tables because search engines are quite powerful these days. But if page content is huge than page with css will be indexed easily in comparision to page with tables. Also css based pages have other benefits like reusability, easyness, fast loading etc.
Just try w3 validator forund at http://validator.w3.org/ Try to maintain a page weight which is around 100kb max. If you didn't get any error reported by the validator and the page weight is okay, there shouldn't be any problem.