Ok, let us quote:

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Quality guidelines - basic principles

• Make pages primarily for users, not for search engines. Don't deceive your users or present different content to search engines than you display to users, which is commonly referred to as "cloaking."
• Avoid tricks intended to improve search engine rankings. A good rule of thumb is whether you'd feel comfortable explaining what you've done to a website that competes with you. Another useful test is to ask, "Does this help my users? Would I do this if search engines didn't exist?"
• Don't participate in link schemes designed to increase your site's ranking or PageRank. In particular, avoid links to web spammers or "bad neighborhoods" on the web, as your own ranking may be affected adversely by those links.
• Don't use unauthorized computer programs to submit pages, check rankings, etc. Such programs consume computing resources and violate our Terms of Service. Google does not recommend the use of products such as WebPosition Gold™ that send automatic or programmatic queries to Google.

Quality guidelines - specific guidelines

• Avoid hidden text or hidden links.
• Don't use cloaking or sneaky redirects.
• Don't send automated queries to Google.
• Don't load pages with irrelevant keywords.
• Don't create multiple pages, subdomains, or domains with substantially duplicate content.
• Don't create pages with malicious behavior, such as phishing or installing viruses, trojans, or other badware.
• Avoid "doorway" pages created just for search engines, or other "cookie cutter" approaches such as affiliate programs with little or no original content.
• If your site participates in an affiliate program, make sure that your site adds value. Provide unique and relevant content that gives users a reason to visit your site first.

If you determine that your site doesn't meet these guidelines, you can modify your site so that it does and then submit your site for reconsideration.
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Here Cloaking, sneaky Javascript redirects, and doorway pages is an important page.

Now remember, this may be Guidelines for a Web 1.0 even before Google used AJAX technologies themself. How do you think Google maps and Google suggest would function without AJAX technologies?

If you can not use i(Frames) I think this is a good alternative. I already wrote about this months ago on my own site, (see third link in my signature).

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When ( if) you (already) understand JavaScript and JavaScript Objects, the natural next step is to learn PHP. PHP is a powerful language that support the most important database plattforms as MySQL, PostgreSQL, Oracle, Sybase and MS SQL server. As an example, consider you have a database connection class for MySQL and PostgreSQL. Both share a common method (API), query. Then you may use the same code on different database servers. I can also highly recommend the Sitepoint book: "Build your own AJAX Web Applications." That is another soft introduction to object oriented programmen where you learn a lot of technologies in addition to developing your own web applications. In addition it has explicite sections on how you shall make accessible web applications for disabled users. The idea is to show content for people with disabilities using simple CSS stylesheets and hide that content for able users. Excellent book where you learn much.
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Note:
Technologies evolves and SE's have to pick up. Neither way, I can not see problems using different stylesheets, unless you use it to improve / manipulate your SERP position or your ranking.

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