You're going to need a bigger amp than that, even if you plan on micing the amp. Settle for no less than 50 watts, perferrably 100+. You can get a 120 watt Crate GFX212+ from musiciansfriend.com for $419. Its a good amp for metal and a phenomenal value. Don't be suckered into buying gear without looking in the right places, you can save a ton of cash by shopping smart. Call 1-800-776-5173 to get monthly Musicians Friend catalouges for free, and check the reviews at harmonycentral.com before buying something to get an idea of the quality/sound of the prouduct you intend on purchasing. Or you can consult a "gear expert", like me.
Also important: Don't be suckered into buying something based on brand hype (ex: anything Fender related, especially since you're interested in playing metal. Avoid Fender guitars and amps like the 10th plague on Egypt).

If you can't afford the GFX212, they have a 65 watt GFX-65 combo for $329