There are now several types of LCDs: PIS, VA, TN... But I have trouble to find what LCD type Dell Latitude D530 has, as it is not written in the specs. Maybe at the time of its release there was only one LCD type? But actually this LCD is very good with colour consistency from different angles, so it is not as easy to find out..
It was a TN. (I used the el-cheapo D530 at one of my earlier jobs.)
The D series is a value range, and never used any higher end components so IPS and VAs are out of question. Plus we are talking circa 2008 here (That's when I got my unit, in India so it must be older than that).
EDIT: Look at it from top, even from 15 degree angle the screen should start getting darker. Tell tell TN signs.