The region of your Gamertag will not lock you out from playing region locked games. That is determined by your xbox360's region ie ntsc-u/c, PAL, Ntsc-J.
Couple of things to bear in mind when determining which gamertag to get.
Microsoft points are region locked for redemption purposes. However, once the MS points are on your account, you should be able to buy whatever is visible on your marketplace. DLC is rarely region locked with some notable exceptions such as gears of war which hates Malaysian IP addresses and the latest example being the dead rising 2 prequel. There have also been some arcade titles recently which have been slow to appear on the asian marketplace.
If you don't have access to a credit card, then go for an SG gamertag as most retailers/resellers in malaysia and singapore sell these cards.
If you have a credit card, there are various online outlets where you can get the points from, such as play-asia.com, offgamers.com and so on.
in terms of price, EU is RM164.75 for 4200ms points, US is RM162.63 for 4000ms points 12 months gold is RM168.37 from offgamers.com. For asia play-asia sells ms points at RM133.36 for 3200 ms points and gold subscription is RM152.
Xbox live subs are not supposed to be region locked but I have experienced problems redeeming asian codes on my EU xboxlive account.
thx for the advise man really appreciated it. So if i'm a creadit kind og guy go for US or UE account but. some game can't be play from U/PAL so i got this problem. My console is asian by the way. so well SG then cash is better then credit card and thx for giving me this site to buy 12 month gold subscription u help alot