I always get complimented on my clothing, and it really isn't too hard to "dress well". I don't even have any expensive clothes, most of them I found at various discount stores and the like, you just gotta look.
The most important part of dressing well is getting clothes that are a nice fit I have a large number of different coloured/patterened dress shirts, which I LOVE to wear, because they fit so damn well and look great on anybody. I mix up what I wear daily,
but this is my favourite style to rock >
http://www.details.com/images/details/features/100105/tuckShirtv.jpg .
Again, it's all very personal, but whatever you do, please make sure your clothes look good together. There's no point in having a lot of nice shirts if your pants don't even match and look like crap. Shoes should match or at least go well with the colour of the shirt. And wear nice shoes, ALWAYS. Unless you are going for a jog or getting ripped at the gym, put the runners away. Sweaters are nice, I'm not a fan of the ones you linked to on your opening post, but if they fit well, do whatever you want.
I recommend you pay premium for jeans, since nice jeans will go a LONG way. Paying $200 for a pair of Diesel jeans may seem like a lot, but for the amount of time you can wear them, it really pays off. Having your own style will give you more attention and makes you stand out more than simply following a crowd (dressing like every other person you see).
*Edit: Check this article out
http://www.kinowear.com/blog/40-common-mens-fashion-mistakes-to-avoid if you haven't