Forum Moderators: not2easy
When it comes to browser support, I'm not sure what you're getting at, but all modern browsers support CSS to at least a certain degree (internet explorer 6 -unless you count older versions, which are hardly used- is pretty much the worst, and aside from it's hundred bugs, it supports it fine), enough so that tables are not required for webpage layout.
When it comes to being semantic -websites using proper elements for their meanings- tables should only be used for tabular data. This essentially includes things which have multiple columns and/or rows which can be looked up, sorted, etc.
There are many advantages to using proper div-based layouts for websites, and few downsides (downsides which will disappear with CSS support improving).
Whether you use tables at all, just for tabular data, or for page layout, you pretty much MUST use CSS to some degree (it may be minute, or it may be large) regardless. CSS is used to easily style things which may (or may not) be repetitive or tedious, making web design much easier to manage. There is no redundancy in using CSS and tables whatsoever.