I would go with DMGenie personally. GMGen is interesting but personally I feel it's strongest feature is if you are not running windows, there is atleast a tool for you and lets not forget it is free. If you are using a flavor of windows and do not mind paying, DMGenie is amazing. One of the best features of GMGenie is the guy coding it, the guy does listen to the users.
But like Soulcatcher stated, it really depends on what you are looking for in an application. I can tell you this without talking bad about all the different applications, I have purchased them all; DM Familiar, DM Genie, Etools, Campaign Suite and RPM (Not forgetting but didn't pay, CMP's free products). In the end, I have them all uninstalled. I found most applications seemed to be designed by people who do not play the game (This is an opinion). With a few, I found it to take nearly twice as long to do something on a computer then it would by hand.
So first thing you should do is figure out what you want the software to do on the laptop and then note down the features you need to assist you in running your campaign. If you are dealing with PC and NPC management, make sure it can handle all of your feats, spells, classes, PrC's, etc. etc. If you want to print information, ensure the output you wish to see if available. This is pretty important because you waste your money and your time, such small things like, generating NPC's is a none existant feature. Almost all such animals are incomplete or worse, incorrect. *laughs* I can see why now though, I started coding an NPC Generator about 2 months ago and I can first hand state; what a monster. This is why I am stating to make sure you know what you want and the program has it. I DM for 3 campaigns and my biggest time killer is game mechanics for NPC's, now that my program is starting to come to life I am spending more time on the story and less on the D20 rules. For example: one of my groups were attempting to destroy a demonic temple and I had to come up with all the different NPC's inside it. Which came to about 30+ half fiends plus others. I was able to create all the stat blocks in under an hour.
You are off to a good start, asking questions on here before buying because there are many on here who either develope these applications or have purchased them.
