Yes, you can, and it's usually fairly easy, at least with modern operating systems and browsers.
For the setup you have, which is probably the most common combination these days, all you have to do is click on the Tools menu at the top of Internet Explorer, then select the Internet Options option. (You can also get to Internet Options from the Control Panel.) At the bottom of that dialog box, you'll see a button marked "Languages..." Press that button, and you'll see what language your browser currently is set for.
Chances are that the only language listed there is English. To make certain sites appear in Spanish, press the "Add..." button to see a list of languages. Select Spanish [es], and then you'll see both English and Spanish listed as language options. You can change the order of the languages; if you put Spanish above English, then Web sites that are available in both English and Spanish will display in Spanish. If they aren't available in Spanish, they will display in English (or whatever language they're written in) as usual.
When you see the list of languages, you'll also see Spanish variations such as Mexican Spanish and Argentine Spanish. If you prefer some variety of Spanish, you can additionally select it and add it to the list, then place it on top. This will make a difference very rarely, as very, very few sites have multiple Spanish versions.
Making this change does not affect the language used in the browser menus, only the language in which pages display.
The procedures are similar for the other common browsers, including those on non-Windows platforms:
- In the current version of Opera, select Languages from the Preferences menu. You can then add Spanish to the list and move it to the top.
- In the current version of Mozilla (on which the Netscape browser is based), select Preferences from the Edit menu, then pick Languages from the Navigator submenu. You'll then see a dialog box that lets you add Spanish. (This feature has yet to be implemented in Mozilla Firebird, although advanced users can manually add language preferences in the user.js file.)
To see if your change in language preferences has worked, simply go to a site that offers content in multiple languages based on browser settings. A popular one is Google. If your changes worked, the Google home page (and all search results) should appear in Spanish.
Note that this change works only with sites that recognize your browser configuration and act accordingly. For other multilanguage sites, which usually display in English by default, you'll have to pick the Spanish-language version from the menus on the site.

