I'm buying a 15.6 Toshiba laptop for work (no gaming etc.) but want to connect a 23 inch display to the laptop's HDMI port when I'm home. Will it make a difference in the resolution if the laptop has a ATI Mobility Radeon HD 4250 or a 5650? And is the graphics card the determining factor in external monitor display clarity?
The HD 4250 will support your monitor's resolution. The primary difference between the HD 4250 and HD 5650 is that the HD 5650 is a much more capable video card for playing games. However, playing games @ 1920 x 1080 with a Mobility HD 5650 is not ideal, but doable.
Thanks a lot for the quick reply. If the laptop is 1366 x 768 can I assume the 23 inch external screen which supports a max res of 1920x1080 will get better than 1366 x 768? Will it be comparable to getting a typical desktop? Also will I get the same resolution and clarity with an integrated Intel HD, for my purposes?
It should look the same, even with Intel Intergrated HD. I should note that some Intel HD chipsets have issues with some resolutions (widescreen ones in particular). These are older LGA 775 chipsets so I imagine the issue is fixed with the Core i series and newer drivers.