1.  Like building a house, the computer is only as good as it's foundation.  Therefore I always recommend the best case and motherboards.  Stick with well known name brands.   My personal favorites are FIC and EPOX motherboards.  Only use cases with 250 watts or larger power supply.  Look at the switches...if they look cheap, then they probably won't last long.  Plan on spending at least $50 for a good quality case.

2.  Stay away from motherboards with integrated video and/or sound.  These usually aren't as reliable.  It's usually tough finding the drivers and their compatiblilty is limited.

3.  Buy the fastest processor you can afford.  Make sure the motherboard can support the processor you choose.  It's easier to pick the processor first for this reason.

4.  Buy the best video card you can afford.  A computer is only as fast as it's fastest part.  You want to avoid bottlenecks.  Pick a video card with a true 128 bit processor and you will be surprised at the speed.  Try to get a well-known brand such as Diamond, Voodoo, Creative, or ATI.

5.  The memory should have a lifetime warranty on it.  This is not hard to find, and usually you can get it from the same vendor as the processor.  Buying as much as you can from a single vendor will cut down on shipping costs.

6.  Storage is something you need not skimp on.  Buy the biggest hard drive you can afford.  Stick with Seagate, Quantum, or Fujitsu name brand.  These seem the most reliable drives.  Also, get the fastest type available...currently Ultra ATA/66.  Be sure your motherboard supports it.

7.  I recommend the LS-120 drives to everyone.  They read both regular floppies, and a special disk that hold 120 megs of data.  While they cost around $100, by the time you buy a Zip drive ($100) and a separate floppy drive ($15 to $20), you come out ahead both on cost and space.

8.  I also recommend you splurge and buy a CD-RW drive and a regular CD-Rom.  The RW stands for Re-Writable.  This means you can erase and write over data on a CD.  The CD-Rom should be at least a 40X or higher.  Memorex, HP, GoldStar, and Teac make excellent products.

9.  If you need a modem, then I recommend U.S.Robotics (now part of 3Com).  Any of the fax modems are excellent choices.  Stay away from the so-called "WinModems".  They have some compatibility issues to work out.

10.  If you are using Cable modem, or have a home network, then you need a Network Interface Card.  I recommend 3Com, but they can get expensive.  I use one from NetGear that seems to be pretty good.  Whatever you get, make sure it's a 32-bit PCI card.

Conclusion:
A good computer will last for at least 3 to 5 years, or more, depending on your needs.  It makes sense to spend the money now rather than having to upgrade later.  It also saves a lot of aggravation, frustration and irritation!