Dell's 9400 is a good machine. However, other users on this forum have recommended not using windows vista. So, see if you can get the 9400 with XP, instead. Also, get it with a 256 video card, since the memory is otherwise "shared" with the video.
From what I have heard about the Macbook Pro, I will be tempted to go to the other side, next time around.
AC19(9001), 27" iMac i7, 12 gb ram, ATI Radeon HD 4850 512mb, OS 10.12.6