Ok first off do not waste your time or money by going to alienware which I will explain in a minute.
Here's what's going on right now. Intel just released its "Core Duo" processor which is a dual core Pentium M (Centrino). AMD has had its Athlon 64 X2 on the market for a little while. The Pentium D however, is not yet available in laptops. It has a faster clock speed and bus than the Core Duo, but is dominated by even the 64 X2 4400+ in every category from multi-tasking to gaming. The 4400+ even crushed the Pentium Extreme Edition (Pentium D with HyperThreading) in the same test, even though the EE is more than twice the price of the AMD. Both of the dual-core processors are pretty much only found in 17" laptops by the way, available in resolutions from 1440x900, 1680x1050 and 1920x1200.
Of all the dual-cores on the market, the Athlon 64 X2 is the best when it comes to performance. For battery life, the Pentium M is far and beyond the best choice. For everything else, the AMD is better. The AMD uses slower, more expensive RAM, but its RAM technology is better because Intel did a crappy job with DDR2. In spite of the RAM being slower, the AMD has a 1600 mhz bus, whereas the Core Duo is maximum 667 mhz, and the bus is a large part of system performance.
The Core Duo uses highly advanced power settings that change the clock speed of the CPU depending on what you're doing, which helps in conserving battery life. What the Core Duo lacks however, is the ability to run 64-bit programs. As a software engineer you no doubt know enough about 64-bit programs already, and while they are certainly the future of computing, they are not yet in use and may not be until a few years down the road. If you want to plan ahead for this new technology, then the AMD is the way to go.
Ok so overall, it depends what you want out of it. If you want extreme performance and ahead-of-its-time computing ability, get the AMD. If you need the extra battery life, go for the Intel Core Duo. But whatever you do, PLEASE PLEASE PLEASE do not go to Alienware. It is a total ripoff. They buy their computers from a company called Sager (which buys theirs from the maker, Clevo, which uses very high-quality components) and resells them for $500 more. Dell sells the Core Duo laptops, but uses crappy parts. I myself am looking at the Dual-Core laptops as well. You will have a difficult time getting into one for $2500, as sad as it may sound. If you want the ability to get EXACTLY what you want (you can even get it with no hard drives, RAM, or OS :!: ), go to
www.hypersonic-pc.com - they resell Clevo/Sager just like Alienware, but for significantly less. Get the Athlon 64 4400+ and the storage you need, but do not buy with any RAM included. They overcharge for that. Get 2 GB of Corsair PC 3200 so-dimm from www.newegg.com and save yourself $100. You will have to save up some more money and bump your maximum to $3000 (as opposed to ~$3500 at alienware :x , but your laptop will kick the crap out of most desktops on the market today. Hope this helps.