I agree with the thinkpads, but...
When it comes to gaming and performance, it's hard to find others that can match Dell specs.
Consider the latest models have 4x dvd burners, 128mb video cards, sxga and uxga widescreens, etc., and see what other laptops can have those - maybe alienware? Who seriously is looking into those machines that run over 10lbs and have a battery life under 2 hours.
Also, I looks at resale values, and I think Dell's hold their own. The thinkpads are built great and generally have great battery life, but they won't have the dvd burners and video cards. The thinkpads are perfect for the corporate world, but I think Dell has its place also.
I really can't tell you how great (and fun) it is, and how easy it is to open up a Dell laptop. I literally built a Dell laptop from parts that I bought on ebay. That said, I have never had a problem with a Dell, and when I wanted to upgrade something it was always the easiest job.
Sure compared to a powerbook, or even to a vaio, it may cosmetically not be much, but compare the Dell Inspiron 8600 specs to other PC laptops and you can see what type of deals they are.
Just to let you know, I bought an 8600 for just under $1000.
These were my specs:
1.3ghz Centrino Processor (Pentium M)
512mb DDR Memory
80gb Hard Drive
4x DVD Burner
64mb 4200 Video Card
Integrated Wireless
15" WIdescreen SXGA+ (1680*1050 resolution)
4+ hour batttery
Windows XP Pro
The truth is that this 8600 can pretty much beat the 17" Powerbook that I have in most if not all applications. And the cost is so much less. Sure you may say I will sacrifice looks, and construction. But try to find another laptop where you can have the same specs, and buy spare batteries for $50 on ebay, or an upgradeable 128mb video card that you can swap for another $200.
Sorry, but for a PC laptop user who really knows the PC laptop market, Dell is just hard to beat.
I see many apple users who bash dell, and I wonder how many of them really had one. Did they just follow the forums or something? Doing my research on the 15" powerbooks I saw many people who had issues with them also. But even though many people who posted on forums had problems (that's generally why people post, no?), I'm certain so many more people had great experiences. Considering how many people buy Dells, and how many people are satisfied with them, and buy newer Dells, I'm thinking Dell is pretty good. They, just like Apple, have their sour machines, but I'm sure the ratio is pretty good.
Geez, I feel like a salesperson for Dell. Excuse me for that!! Meanwhile I love my 17" Powerbook

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Thanks for letting me vent a little!!