Wanna buy DELL U2515: some questions,

What is the difference of a Dell U2515H monitor (2560x1440) vs acer 1920x1080 monitor in term of EXCEL use? Target to view more column at the X-axis

Now using Lenovo T410 VGA port to extend screen 1/2 to the acer monitor, is it support or I need a DVI converter?

U2515 only have HDMI and DP, if T410 have DP, you can use it to support max. resolution.