Having been into computers since the mid 1980s, I have been asked by hundreds of people, "What kind of computer is the best?"  What it really boils down to, is what do you need or want it for?  There are some hot brands out there that have the blazing speed of the top of the line machines like AlienWare and Falcon Northwest, but most people will never use this power before it becomes obsolete.  Don't get me wrong, if you are an all-out-gamer who wants the best performing machine at all times, those are 2 names to know.  Most of us want a little of everything like, play some games, burn CDs, maybe DVDs, surf the internet, do school work, small business etc.  If you are HEAVY into graphic design, digital music or CAD, don't cheat yourself; get a MAC.  Most of us choose PC because of the amount and availability of software out there.  Remember when notebook/laptop computers were about $5K?  You can get a great notebook computer today for $1000 - $1200.  The bonus to this, is portability.  A desktop sits on a desktop and because of wires and other periferals has to stay there.  A laptop can go anywhere you need it.  I just bought a latptop to run my business instead of a desktop and I am thankfull for that decision everyday, because I am mobile.  For nitty gritty on what to get look here.  Most computer users will be happy with this configuration: 

The slower processor of  the faster technology. ex.  

Intel Core Duo Processor (1.73GHz/533MHz/2 X 1MB L2 Cache) 

Intel Core Duo Processor (2MB Cache/1.83GHz/667MHz FSB)

Intel Core Duo Processor (4MB Cache/2.00GHz/667MHz FSB)

Intel Core Duo Processor (4MB Cache/2.16GHz/667MHz FSB)

 Choose the one in bold because the Bus (motherboard) is faster.  If you can afford the next upgrade, the one in italics has a 4MB Cache.  "On die" cache RAM does a lot of good for 3d graphics like gaming and rendering.  Do not choose Celeron, Centrino, Duron or the like, they are stripped down versions of the real processors (little or no "on die" cache RAM) 

RAM is crucial, no pun intended.  Get the fastest if they offer more than 1 speed, and get 1GB, if you want to splurge and get 2GB fine.  RAM helps with multitasking and the speed of going back and forth between programs. 

A 100GB Hard drive is a good, 7200RPM is fast, the higher the RPM, the better. 

If you like games, you'll want a video card upgrade, not integrated video. 

If you like mp3s burning CDs ripping iTunes, get a sound card upgrade, not itegrated or onboard sound. 

Try to get an optical storage drive that at least burns CDs and reads DVDs  Some software is on DVDs nowdays. 

Floppies are a waste, get a USB memory drive. 

56K Modems are basically standard and come in handy on vacations. 

10/100 Ethernet is ok, but 802.11 b/g (Wi-Fi) is nice and 802.11n really rocks!  Not just at Starbuck's, home wireless networks are inexpensive and easy to setup.  As  far as operating systems go most only let you choose Windows, I think there is a new Windows version coming soon along with a new version of MS Office.  I like Office but try wwwopenoffice.org for a freeware office set.  For security, I have Norton Systemworks and Norton Firewall.  They work great and I get 'em here on Ebay, never pay retail!!  Here is some other software I like: if you make home movies into DVDs, Ulead Video Studio 9, if you like to burn CDs and DVDs, Ahead Nero Burning ROM and Network Magic for home networks.