while waiting for my virtual tits simulator and office manager to submit his report, i shall devote my time to answering you:



- what is the different with modded & unmodded xbox 360?

Modded allows you to play pirated games. Likewise unmodded only allows you to play original.
The #1 rule in LYN Xbox forum is we don't talk about modded consoles.
The #2 rule is rule #1.


- is 4 gb sufficient or should go for 250gb?
Depends on what you intend to do with the 360.
If you're looking just to play 1or2 games for around 1hr per week, the 4gb will be sufficient.
If you are using it as your main console it is highly recommended to get the 250gb.

- can recommend reliable shop? means that the product is genuine and good after sales service
By now you should realize that all Malaysian video game sellers are assholes. So the key to a better video game deals are to find the one which is the least of an assholes.
(You can never get one to one comparison price with US because MS never launched the 360 in Malaysia.)

There are a few LYN sellers that are REALLY good.
Pbbseller - JB based
Tech2 - KL based
These 2 are great because they undercut Playasia.