Ideally, to run AutoCAD, get i7 quad core, and if doing 3D CAD, need good GPU. Also 8G RAM or more is ideal (8G RAM stick ~ RM200). Also FHD screen is better, as he can see more on the screen.
But your brother budget is pretty tight. Priorities

Asus
A45VS-VX026H, i5-3210M + Nvidia GT645M@RM2199[2.4kg], 2GB, 500GB, W8
K46CB-WX060H, i5-3337U + Nvidia GT740M@RM2199[2kg], 2GB, 750GB, W8, 4-cell, OD

Dell
Inspiron 14-3421, i5-3337U + Nvidia GT625M@RM1649[1.99kg], Ubuntu, 4GB, 500GB(5400rpm), 6-cell; W8SL@RM1899
Inspiron 14R, i5-3337U + Nvidia GT625M@RM1699[2.33], 4GB, 750GB(5400rpm), Linux; W8SL@RM1999
Inspiron 14R, i5-3337U + Nvidia GT730M@RM2099[2.33kg], 4GB, 750GB(5400rpm), Linux; W8SL@RM2299
Vostro 5460, i5-3230M +Nvidia GT630M@RM1899[1.54kg], 4GB, 500GB(5400rpm), Ubuntu 12.04, 3 cell; W8SL@RM2099

Lenovo
G480, i5-3230M + Nvidia GT635M@RM1699, 4GB, 500GB(5400rpm), FreeDOS
G480, i5-3230M + Nvidia GT635M@RM1899, 4GB, 1TB (5400rpm), W8, 2 yrs warranty

Prices are RSP, negotiable.

by the way, nexus, how do we negotiate with Dell?
coz recently i bought online but they never call me.
some people said that before they deliver, dell customer service will call the buyer to confirm on the package?

Dont think can nego if buy directly online. .

1. Preferred Brand - Lenovo
2. Budget - 1k
3. Usage - Browsing, MS Office, Music
4. Preferred laptop/screen size - 14"

Additional Clause: Preferably that it can be found at Lowyat

Chat button.
Dell website:
"Live Chat
our Dell Expert
Mon - Fri : 9am to 7pm
Sat: 9am to 3pm
Sun: Closed "

Don't you ever wonder for the same Dell model, reseller could sell at the lower price than on Dell website? 
Well, if you just pay the listed price on Dell website, Dell will just say thank you very much

I see, will try it out.

Thanks bro!

The specs are a little bit weaker, but if you want, can consider these:
14"
Toshiba
Satellite L840-1056X/XR/XW, i5-3230M + AMD HD7670M@RM1949, 2GB, 500GB, W8SL; 2 years warranty; colors: black/red/white
Satellite M840-1070XR/XW, i5-3230M + AMD HD7670M@RM1999, 2GB, 500GB, W8SL; 2 years local warranty; colors:red/white

Hi Sifu,

Instead of above suggestion. Can u comment on this model:

- Satellite L850-1024X/XR/XW, i5-3230M + AMD HD7670M@RM1899, 2GB, 500GB, W8SL, 2 years local warranty, RM50 shopping voucher; colors: black/red/white

The price is much lower with 15'.
But how about it specs? 

My sister wants to buy her first laptop. Light user, just light image editing. Since most new laptop comes with windows 8, hope can grab 'older' laptop with great discount with windows 7 or FreeDOS .

1. Preferred Brand - non-Acer, non-ASUS
2. Budget - 1.8 to 2.3K
3. Usage - movie, web, downloading, light image editing
4. Preferred screen size - 13-14"
5. Other preference (not compulsory): Light weight, windows 7
6. Will use LCD TV as screen when watching movie (must have VGA or HDMI port)

Thanks

14"
G480, Celeron 1000M + Intel HD@RM999, 2GB, 500GB, FreeDOS; W8@RM1199
13"
S300, Pentium 997 + Intel HD @RM1199[1.8kg], 2GB,500GB(5400rpm), freeDOS; W7HB/W8@RM1399, no ODD, 1 yr warranty
S300, 1007U + Intel HD @RM999[1.8kg], 2GB,500GB(5400rpm), freeDOS; W8@RM1199

Prices are RSP, negotiable. Shouldn't have any problem finding these models at LYP.

My sister wants to buy her first laptop. Light user, just light image editing. Since most new laptop comes with windows 8, hope can grab 'older' laptop with great discount with windows 7 or FreeDOS .

1. Preferred Brand - non-Acer, non-ASUS
2. Budget - 1.8 to 2.3K
3. Usage - movie, web, downloading, light image editing
4. Preferred screen size - 13-14"
5. Other preference (not compulsory): Light weight, windows 7
6. Will use LCD TV as screen when watching movie (must have VGA or HDMI port)

Thanks

Dell vostro 5460 - buy the free dos version, install window 7

devour sifu is recommending these 
Vostro 5460, i3-3120M + HD 4000@RM1,549[1.54kg], 4GB, 500GB(5400rpm), Ubuntu 12.04, 3 cell; W8SL@RM1,749
Vostro 5460, i5-3230M +Nvidia GT630M@RM1899[1.54kg], 4GB, 500GB(5400rpm), Ubuntu 12.04, 3 cell; W8SL@RM2099

Prices are RSP, negotiable.

Bro nexus, how does this model compared inspiron 14 u recommended me? Since price is negotiable, it may meet my budget of 1.5k and below.

1. Preferred Brand: Lenovo / Acer / HP
2. Budget: Below 3k
3. Usage: Daily multimedia use (movie, music, surfing net) + engineering software (AutoCAD) + light gaming (Dota 2)
4. Preferred laptop/screen size: 15" or above
5. Good reliability
6. Windows 7

Any sifus here can help me? Much appreciated!!! 

Price = around 2k-2.5k
Brand = Asus ,Lenovo, Dell, Acer, HP, Toshiba
Purpose = Uni purpose. (doing assignment). Slight gaming (Left 4 dead 2),dota 2,watching movie
Others (Must) = Screen 14",not too heavy, thin,touchscreen
Optional:SSD

thx