If you want to connect the displayport on your Thinkpad laptops to a monitor with dvi input, then this is how you do it.
Note: Following are the Thinkpads with displayport
-T500, T410, T420, T400s, T410s, T420s, T510, T520.
-W500, W510, W520
-R500
-X200/X201 Ultrabase, X220, X220t
-X301
Not sure what displayport looks like?

This is how you do it, get a displayport to dvi converter like this.

http://www-307.ibm.com/pc/support/site.wss/MIGR-70
Then connect your regular DVI cable to the displayport converter's DVI out side.
You can now use the displayport as if it is a DVI port.
P.S. Lenovo Displayport to DVI converter is a single link version, so it is only designed for resolution up to 1920 x 1200. You would need a Displayport to dual link DVI active converter to support dual link high resolution LCD such as the 2560 x 1600 & 2560 x 1440 versions, which you can get from reputable online retailers and some computer stores.