I would go with UltraEdit and either mysql or postgresql. To do a templated site, use PHP (just an option), then you could just call the templates from a table in your db. As for the strain on your system... Just make sure that any results that you fetch, you clear as soon as you're done with them....
in PHP using MySQL it would be mysql_free_result(resource_id);
That way, your massive result will not bog down while the rest of the script loads... RAM is the most important aspect when dealing with db select statements... lots of ram means no strain
[edit: afterthought] If you do a lot of JavaScript and client side scripting, do a test in NN4.7.x as well as the new gecko engine. I've found that many of the client side scripts break on this new engine...[/edit]