You NEED a suit in this current climate. Anyone who says otherwise either hasn't got a job, or has been in theirs for a while. Take it from someone who in this year alone has had five job offers (ie Me)
You really need to get your look 'right' for your job interviews/assessments/informal chats. Doing this beforehand gives you a larger advantage over other candidates. First impression is EVERYTHING!!!!! you go into someone's bedroom and it smells of toilet business - you will forever label that person as having no house training.
First off, get yourself the whitest of white shirts. Don't skimp here, some cheaper shirts will deteriorate quite easily and won't have that 'gleam' when sunlight shines onto it. I recommend grabbing a shirt which requires cufflinks too, it just 'looks better' - even if its for a P/T filing clerk job, they will remember this and see you are taking the opportunity very seriously.
Tie, go for something neutral ie i'd stick with gray with perhaps a colored stripe pattern. don't go for something too colorful and definately don't go for anything humerous - they will just see it as immature. Don't go for just a plain color either, it just looks too plain/ordinary.
Suit, you need to get a decent one that's going to keep you sorted for interviews - I recommend black or some sort of charcoal grey that looks almost black. Don't go for navy blue with pinstripes, you'll just look like an ex salesperson. You may want to consider grabbing a machine washable one. They look just as good and less £££ goes on dry cleaning. Plus you can clean it in an emergency.
When you've chosen and purchased your suit, the pockets will most likely be sewn shut (Your supposed to tear the stiching to open them up) Dont! I find if you refrain from opening them, the suit looks neat & tidy with no sagging pockets. This will also prevent you leaving packs of mints in there etc.
Sizing is important too. Do not get trousers too long or too short, they noticed this on one of the contestants for dragons den and took the pee. This applies to everything, if everything is too baggy, you'll just feel stupid. Too small and it just isn't comfortable and may tear. Make sure to try things on in store, take as long as you need and ask the sales assistant for their opinion or take a friend/relative who has more experience with tailoring.
Shoes are also important. Black leather is a must. Consider grabbing ones without laces - they are easier to polish and just look modern. Something with style I would say also. I always wear my italian style 'curl-ups' as I like to call them and chances are the interviewer will engage with you on the subject of them which gives you some high ground from the start.
Off Topic, but are we allowed to post links to sites which sell clothes/stuff unrelated to computing etc???