Here ya go...
Motherboard – I'd go for the ASUS A7M266. The Gigabyte GA-7DXR might be worth a look – it has more features – but might be hard to find in stock.
You'll need PC2100 ram for that motherboard. Kingston, Crucial (Micron), and Corsair are the only brands to trust. You do not need registered ECC memory. Get the unbuffered. For a hundred bucks, you can get two 256M sticks.
A SCSI interface is a luxury most people do not need. If you use software that is disk intensive (recording digital audio, ripping movies, web server) you should consider a SCSI system. Otherwise save a pile of cash and go IDE.
For CDRW, go for the Plextor 16x10x40, and get a Pioneer DVD drive.
The IBM Deskstar GXP60 drives are excellent. 60G for about $150.
The OEM Athlon 1.4G SocketA is cheap! Add a Thermaltake Mini Copper ORB to keep it cool.
Video card – Top of the line is probably the Asus V8200 Geforce3 Deluxe. If you do not need the fastest video card available for gaming, save $$$ and get an Asus V7700 Pure 32MB Geforce2.
I've built six PC's using the InWin Q500 full tower case. It is plain and inexpensive, but very good quality and BIG! Only gripe is you must remove the top cover to remove the sides. Not a big deal unless you like to swap hardware often. Do some searching on deja.com to read about a particular MB/case combo before you select the case.
Get some case fans if they are not included with the case. The Q500 has a number of locations for 80mm fans. Two should be enough. Sunon makes decent fans, so does Panasonic (Panaflow).
Teac Floppy of course.
I haven't bought a modem in a long time. Just make sure it is not a winmodem – those take CPU horsepower and do not work with Linux.
A good speaker system will last for years, so might as well splurge on the best if you can afford it. The Klipsch Promedia 4.1 system looks awfully interesting. It is THX certified, which means it is very loud and astonishingly clean. An incredible bargain at $300.
The SB Live 5.1 is cheap and has decent sound quality. It is noisy, though. There are many better sound cards, like the TB Santa Cruz, Hercules XP, and some very expensive cards designed for pro audio use. I have two soundcards in my PC. One is a SBLive 5.1 for general use, and the other is a Yamaha SW1000XG for listening to MP3s and making music with Cubase.
But I suggest starting with the SB card, then look for something better if you are bothered by the sound quality.
Total price should be $1500 to $1800. Considerably more if you do SCSI.