These Anandtech buying guides are just awesome. Rather than writing my own, I'll just do the difference in opinion I have compared with their analysis:
h2. High end
See AnandTech: Buyer's Guide: High End System - July 2004 for base recommendations.
Here are the deltas to get a machine cost (without monitor) of $2200 but it is the most screaming thing out there right now: * I'd recommend the Athlon 3500+ ($500) instead and just overclock it rather than getting the FX-53 ($800). If you are bargain hunting, get the Athlon 64 3200+ ($270) and overclock it to 2.4GHz. It is the older socket, but performance is really just 2-3% less and quite a bit cheaper.
* The MSI K8N Neo2 comes out well in either socket 939 or older socket 754 versions at $150 * The OCZ 3700EB is a real winner at$370 for 2x512MB or get the OCZ 3500 EB ($300) and just slightly less performance. Both overclock well to DDR433-450 (217-225MHz bus vs. standard 200MHz). * On video, benchmarks disagree a little, but either the GeForce 6800 Ultra ($540) with 16 pipelines, 400MHz GPU, 1.1GHz DDR3 RAM. The vanilla 6800 ($300) seems like a good price/performance leader. * Agreed on the monitor with the very fast Samsung 193P ($750 shipped) as a great 19" monitor
* Agreed also on the case and power supplies. The Coolermaster Praetorian ($110) and the Antec True Power 480W ($85) are expensive, but will keep a big system cool and stable. Don't skimp on the power supply in particular.
* Sound and speakers. I'm actually not that expert on really wonderful sound and would probably use what's stock on the motherboard.
* On the disks, think you should get a single Western Digital Raptor 74GB ($200) as system drive and then a big Hitachi 7K250 250GB ($190) drive for data. These are two of the fastest drives around according to storage review.
* On optical, disagree with the choice and think you have to get a dual layer (9GB/side DVD writer). The NEC-2510A ($85) looks like a great choice. h2. Mid-range See "Anandtech":http://anandtech.com/guides/showdoc.html?i=2087's June piece, here are the deltas at$973 (excluding monitor, speakers, keyboard/mouse, that is assuming you are just replacing the system unit):
* CPU and Motherboard. Agree with the Athlon 64 2800+ ($172) and the MSI K8N Neo Platinum ($131). You can overclock this to 2.4GHz usually. Stick with the 754-socket, this is going to be cheaper, but you get the fast 64-bit processor at about the same speed with overclocking.
* Memory. Agree with 2 X 256MB OCZ PC3500 EL (Enhanced Latency) CAS2.0. Price: $120 shipped. These you are run reliably at DDR433 (217MHz bus). * Video. Disagree and think you can get the ATI 9800 PRO 128MB for around$200 given the X800 has now shipped. A good performing video card if you play games. Otherwise, get a really cheapo one since video performance doesn't matter for running Office or browsing the internet.
* Case and Power Supply. CaseEdge TS1 Mid-Tower Price: $40 shipped from "PC Club":http://pcclub.com plus an Enlight 360W power supply ($35) seem fine.
* Disk. Would get a bigger hard drive given pricing. The Hitachi 2K250 ($190) is a great buy and is super fast. Or get the Western Digital WD1200JB ($80) if you are really economizing.
* Optical. At these prices, I'd just get the NEC-2510A dual layer DVD writer. You'll need it later ($85) h3. Low end Ok, this is the cheapest decent system based on "Anandtech":http://anandtech.com/guides/showdoc.html?i=2077 to get a total system unit price of$536.
* CPU. Take both the Athlon XP 2500+ ($75). You can overclock to get a little more performance. The mobile version BTW has the ability to run much cooler ($88), so is well worth it.
* Memory. Take the secondary recommendation of the OCZ PC3200 EL 256MB ($70). If there is anyway to afford it, go to the 512MB version ($120). Memory is a big driver of performance
* Motherboard, Video, Power Supply and Case. Instead of getting a motherboard, case and video, you should get the Shuttle SN41G2 ($200). This is a box that has it all. Otherwise, if you want a big case, get the ASUS A7N8X-X ($75), Sapphire 9800SE ($48) and Foxconn Super Case 100-G2-P4 Mid Tower Price:$45 shipped with AMD approved power supply. This will be bigger though than the Shuttle and therefore upgradeable.
* Disk. Agreed on the Western Digital family, but best price per MB right now is the WD1200JB ($80) rather than the 40GB or 80GB versions. * Optical. Get a vanilla CD-RW and DVD reader drive say the Lite-On 52x32x52x16 Combo CD-RW/DVD-ROM drive ($48). But if you can afford the splurge, getting to the NEC drive gets you DVD writing for backups and movie making.