I'm running 4850 on 24" LCD 1920x1080. Sluggishness is noticeable at Very High setting. Somehow previously I can run smoothly on 19" LCD. 
Hopefully my new 4870 will get rid of this sluggishness

Sorry for the noob question, but if you're a gamer, is 16:10 or 16:9 better? Is there a significant difference between the two?

For game and movie mostly is using 16:9 which is 1920*1080, so is almost 1:1 mapping and compatible. But if for browsing and doing office work then 16:10 will better since you have another 220 pixel to view ur webpage or document. 

5:4? Or 4:3?

I'm thinking of getting one of those 16:9 LCD but my 4850GS will definitely not able to run them at the native resolution maxed out. Wonder if I can run half hd instead? 1280x720 or that will need to depend on games? If play those with 16:10 means err fatter screen display? or can set so that the screen doesn't stretch it but having the black gap on the sides?

If 22", you've stuck with one choice.

24", it's about RM50 difference and the s2409w you get more real estate.
Anyways, the Samsung T220, is it glossy or matte screen? With the prices of 22" monitors dropping so much lately and 21.6" cropping up, it's really hard to make a choice for the 22" segment isn't it?

I'm also surprise we see Full HD logo in the website. I thought only 1920x1080 will be Full HD.