Presentation goes a long way, which is something I preach more than practice. I think like most guys, necessity and convenience have guided my style more than anything else. My plan over the next year or so is to evolve beyond simply confirming that I'm wearing pants before I leave the house.
As superficial as it may be, looking good counts. Imagine if someone at work sent you a sloppily written e-mail, or put a blueprint on your desk with wrinkles and rips and coffee stains all over it. Doesn't mean the content is seriously compromised, right? But it does influence the way it's perceived by most people, even by the ones who don't consciously feel they're superficial. The business world is saturated with competition in every direction, so every detail counts, and given a choice of similar, competing products (or businesses, or employees seeking promotion), most people are going to go with their best impression. Unfortunately, it's an environment that hides a lot of fakers: people who can't do their job but fly under the radar of better judgment because they're wearing the right kind of camouflage.
Most people don't have to buy an expensive suit to get by (with the exception maybe of your own wedding, where you might justify going the extra mile). An inexpensive suit can still look great, but don't buy it off the rack - let the tailor take your measurements, and pay the couple bucks extra for alterations if that's the deal (sometimes the cost is included in the purchase). This goes for buying just a jacket or dress pants, too. Get recommendations on tailors and suit brands from people at your work (or friends) who look good, because gettng a bad suit is like getting a bad haircut.
My advice is to look good, and to get someone to help you with it (girlfriend, mom, dad, wingman) so they can confirm it and you don't have to obsess about it. Whipping out the old iron goes a long way (seriously). If you're like me and you lack all sense of style, copy someone elses. So what if you're a faker when it comes to looking good? That's better than being a faker at everything else. The impression you'll give the world is that you're the kind of guy who doesn't mind taking care of details, as oppose to the kind of guy who can't be bothered.