Website advantages over an in-game window...
1) Generally more/nicer formatting options with CSS, tables, etc.
2) Easier to cross-link text and images (everything is a button in HTML)
3) Updates are immediate, no need to download a zip or run a patcher.
4) In many cases, you could avoid having to update info yourself by simply linking to another resource on the web that has that info.
5) Immediate feedback. With web forms, you could give your users the ability to comment on content, without needing to tab out of game. This might be corrections, additions, or requests for new stuff.
6) Your very useful resource would be available while not logged in.
Disadvantages...
1) SOE's browser could break, but I honestly don't see that being any more likely than a custom window breaking.
2) The browser eats up system reources. Someone would have to run some tests to see just how loading the browser with 1 page of your content compairs to loading the custom window with ALL content. My personal impression is that the performance is very similar if the web page is kept relatively simple.
3) Can't execute EQ2 scripts from a web page, so the handful of features you've included that do execute scripts would need to be ditched or dealt with in a custom window.
Overall I think the advantages outweigh the disadvantage. If you decide not to go the web wrote, I may end up doing it myself but I really would rather not steal your thunder
