I got my own computer business in Canada (Quebec) and I can help you get a good machine. 1st, don't buy a ready-to-use computer such as HP, Compaq, IBM or whatever if you are a gamer. A "home-made" computer is always better and may be cheaper because you wont have to pay for things that are useless to you... Of course, you have to select proper brands in order to have a quality computer. I'll go through all computer parts to make a basic computer.
First of all, I suggest you to talk with your friends in order to choose between Intel Pentium or AMD Thunderbird / Duron, which are the CPU. From my point of view, both Intel and AMD are pretty good CPUs. Forget about Intel Celerons processors, don't buy a Celeron, this is the slowest thing ive ever seen. Intel processors are more expensive than AMD ones. Therefore, Intel is the most stable cpu you can get. AMD is also pretty stable but you may (or may not) have some compatibility issues with new Graphic cards especially and some USB devices. AMD is way faster than Intel cpus at same frequencies (ie: 1ghz Intel < 1ghz AMD in term of speed). So my suggestion would be to buy a AMD Thunderbird 1.3, which is about 30$ more than Intel PIII-1ghz.
Motherboard: This is the heart of your computer. Majority of bugs / slow moments / incompatibility problems may be cause of a bad mainboard. From my point of view, Asus is the best price/quality motherboard on the market. To fit with a 1.3ghz, you must buy the ASUS A7A266, which allows you to get DDR memory or PC133 memory, depending on what will be the main use of your computer. DDR memory is often use for network servers or for people who will use 3D applications or enthousiasts gamers.
FAN: Let's talk about this important part of your computer. There is 2 types of fan in a basic PC. First, you have the CPU FAN, which is attached to your processor. this fan is almost the more important part for a healthy computer. A good brand of fan will prevent your cpu to overheat during its operation and will maintain it at a lower temperature than noname brand, which will longer the life of your processor. Of course you may not find this brand in your local computer company, but I suggest you the ELAN Vital (FSCUG 3) or the Cooler Master DP5-6H11, which are noiseless and temperature effective compared to noname brands.
You also need a second fan to fit in your tower. It's called secondary fan. Noname brands are good to put there. It's a MUST anyway.
Memory: You'll need PC-133 memory to run your computer at a good speed. I suggest you to buy 256 megs of RAM, which is cheap nowadays. Almost all blue screen of death problems and computer problems such as random reboot or freeze is directly caused by bad memory. Therefore, it's really important to buy a MAJOR brand in order to have a stable computer. Major brands are: Kingston, Corsair, Viking and Hyundai. I highly recommend Kingston for being the best memory brand ever made and available almost anywhere in the world.
Tower: To answer to your question, the tower is also important when you are buying a new computer. Not important in term of design, but in term of Power Supply. 300W power supply is a MUST. 250W supplies are too low. A mid-tower should be your best choice. Although it must have some good air-traps or holes to let the air / fans functionning properly.
Hard drives: I suggest you a 40Gb HD. With 40gb, you should have way enough space for storing CD images for multiple burning process. A 7200rpm drive is also a must-have, since its speed is much more faster than old 5400rpm drives. ATA/66 (which means 66megs per seconds) will be enough for your needs. ATA/100 drives are usually more expensive and doesn't really improves the overall transfer rate / speed of your computer.
A good brand to buy is Western Digital WD400. Maxtor, Quantum, IBM, Seagate and Fujitsu are good brands too. The drive must be IDE of course.
Video card: okay, this is a big part of your computer. But again, if you don't plan using 3d Apps then you can save big money. My choice would be: Asus V7100. This card will give you real nice graphics on any games and pretty good performance too for its low price.
Sound Card: Sound Blaster Live! Value is by far the best choice... Available at around US$60 .
CD-Writer: I suggest the Plextor 12/10/32a. This is what I have. It just rock.
CD-ROM: Although your cd-writer can read cds, I highly recommend you to buy also a CD-ROM. That way you wont use your burner len for reading music / data cds and then you wont decrease the life of your cd-writer. A good and cheap choice is the LG cd-roms. Asus 50X cd-roms are not bad too.
Modem: If you are not connected with a broadband connection, then you may need a new 56k modem. USRobotics is a good choice, but ACER FM-56PM is even the same and its cheaper.
1.44: Don't forget your floppy disc!
DVD-ROm: May be a good buy. But, if you do not plan to watch DVDs on your computer monitor, then its useless. Unless you buy a TV-OUT graphic card and plug it to your Living Room TV. If you want to buy a TV-OUT graphic card, then buy the ASUS V7100/T model which will be around 50$ more than the original V7100.
Well that's about it.. I hope you'll find these informations useful and will guide you trough the rest of your buying plans... If you need more infos then contact me at : email@example.com.
Have a nice evening!