To be honest, I don't have the answer to this question, but there are several things you can do.
For one, you won't need to rely on this if you purchase a 3rd party WNIC (like the ASUWO36H whcih works rather well, as do most otehr WNICs with the RTL8187 chipset from Realtek).
You could also do what I've done in the past. I went into a local Best Buy and found a display laptop vof the same line as the one I planed to purchase. I booted to my Backtrack USB and ran aireplay-ng -9. This command tests for injection. For more on this command see the man pages, http://www.aircrack-ng.org/doku.php?id=injection_test.