Assuming that your site is going to be on the www and not just for personal use, you need to set it up in such a way that viewing it will be a good experience for most vistors. It is virtually impossible to create a site that will render perfectly on all equipment and in all versions of all browsers. So the next best is to aim for the greatest possible audience. If your site renders well in IEv6 Firefox v1.5 and Opera v8 then you will be accommodating most visitors.
Laying out a site using Tables was the default way of doing things before CSS, and is still used by many professional developers. Positioning graphics using Tables is not difficult. For a simple site (e.g a family site with pics of your kids or your last holiday) this is probably still the most practical way to go.
If you intend to build a number of sites or even earn a living from website development then you should learn CSS and you should layout your site using CSS. You will probably still find that you will occasionally "cheat" and use a small table for a little layout job, but CSS is really the way forward.
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