My site is in html with several tables.
Can the change to css cause aging delay?
I don't understand if my pages would be considered as new.
The URL's will remain unchanged.

Aging delay? Like the "sandbox"?

Nope. The page is still where it's been. It would just have been modified which is (usually) a good thing.

In the case of a CSS layout replacing tables, it would be faster loading, have a better ratio of text to code and I'm led to believe the SE's would like it an unmeasurable fraction of a tiny byte better..

Thanks for your reply. I visited your site. You do indeed have some neat gift stuff.

I've bought one book about CSS which was over my head but I've ordered another which is by Elizabeth Castro. With her HTML book and some instruction from my daughter, I learned how to make a site back in 1998 using HTML. I've made many updates to my site of educational resources but no major overhaul such as CSS.

Do you have a site to recommend for learning some simple, basic CSS?

My site isn't very techincal but I have learned to do interesting things with tables.
My URL is in my profile.

Thanks for the compliment.  There is a lot of work to do on it yet. It's about the same age as when I registered here (9 - 10 weeks).

The reference I use is "CSS Pocket reference" published by O"Reilly, written by Eric A. Meyer.

I always suggest the same approach starting out: google for the type of basic layout you'd like (two or three column fluid in your case) and start setting it up in the background index2.html or whatever suits you and work on it until its ready and just swap it out. No pressure. No grief.  The layouts can provide a great, stable starting block to start building on.

Watch out for different display characteristics in the two major browsers, at least IE & Firefox because they handle a few things differently. Tables are a bit more controlling IMO than CSS, but the benefits are many.

You might like to try a few of  these for ideas:
    http://www.glish.com/css/
    http://bluerobot.com/web/layouts/
    http://webhost.bridgew.edu/etribou/layouts/

The Index of my site hasn't any tables, so CSS isn't really restricting. Just takes a little getting used to..

There are a few dozen members here who are happy to help with frustrating issues.

good sites

position is everything
CSS2 Specification
CSS2 Property Index

Thanks for all of the suggestions. I'll work on them. I've already ordered the book and visited the links.
It will take a while to digest it and to change my site. It is about 180 pages.
After making changes, I will ask for a site review (on the appropriate thread) to see if I have followed directions very well.

DMX wrote:

In the case of a CSS layout replacing tables, it would be faster loading, have a better ratio of text to code and I'm led to believe the SE's would like it an unmeasurable fraction of a tiny byte better..

faster loading? possibly. the page will load faster but then the css has to load. most systems cache the css for later use, so make sure the css is fairly global

have a better ratio of text to code - true, but this doesn't help SEO. truth is more along the lines of where in your code the text/content is. towards the top is better. CSS will allow source ordering

led to believe the SE's would like it an unmeasurable fraction of a tiny byte better - i've had big measurable results that its liked better, mainly from source ordering.

But - these observations are just from my experience - remember this when listening to others. what works for some may not work for you. Learn, play, experiment, test and analyse

Hmmm,

It's been my very limited experience that CSS is leaner than nested tables (the way they are often inclined to go) and faster even with the stylesheet in tow. This was the case when I reworked mine, anyway. After the stylesheet is cached, the rest of the site implementing that CSS should be in heaven. 

I don't even have a SEO hat to wear   I was primarily addressing the "aging delay" and tossing in my thoughts on a few of the benefits of CSS, without creating expectations of huge increases in SE positioning. Still, I think, valid.

I understand source ordering fairly well and implement it on mine.

labooks - If you're not familiar, it's sort of rearranging the elements on a page to suit the need because the style sheet is clear where they are to be displayed. So, you could place the main text area first, then the menu, then the header and so on. Agreed that it is an important benefit of CSS.

And last, I whole heartedly agree that one has to take advice from forums with trepidation. Most of us are fairly adept at one aspect or another of site building or promotion. Not necessarily all of them

So, welcome to the club, so to speak.