good clothes at cheap rate, that being under Rs. 1000? --- Majestic {nearest}
cheap casual clothes? ?(plain tshirts/shirts) -- Majestic
computer hardware at cheapest price in bglore? -- SP Road {no better place}
factory outlets of nike, reebok, puma etc. --- Marathalli...{yelahanka too has some I guess, not very sure}
PROPER north food. cheap, if possible. --- depends on what you mean by PROPER. North Indian food is available everywhere but if by PROPER you mean food made by your mum, then ghar se ek-do dibba saath le aana. lol
North chaat, anywhere? -- everywhere.
Service centre of Dell.-- NO idea.
Few shops like Alfa in Mumbai, where i can get stuff without bills -- dunno what you get over at Alfa. So can't suggest.