give us a budget because i dont know what to recommend. but ill break it down into 3 sections. low price, mid price, and holy crap. oh yeah, this is going to be all AMD because Intel cant be considered for serious gaming right now unless you want to spend a shit load more and get worst results. and as for the memory, save money dont need the fastest because for AMD, cpu speed is king. run dividers.
Low Range:
Motherboard: Chaintech Ultra $74
CPU: AMD 3000+ Venice Revision E $140
RAM: Corsair Value Select 2X512MB $85
Graphics Card: eVGA 6600GT $135
PSU: OCZ Modstream 450 $70
Hard Drive: Hitachi 80GB SATA $50
Burner: NEC 3540A $40
Floppy: Scrub around. Not worth $13
Speakers: Logitech X530 5.1 Surround Sound $50
Sound Card: Onboard Free
Keyboard: Logitech Basic with Mouse $13
Case: Cheapest you can find $30-40
Total: $697
Mid Range:
Motherboard: DFI Ultra-D $125
CPU: Opteron 165 Dual Core $299
RAM: OCZ Platnium 2X1GB $230
Graphics Card: eVGA 7800GT $340
PSU: OCZ Powerstream 520 $110
Hard Drive: Western Digital 250GB SATA $120
Burner: NEC 3540A $40
Speakers: Logitech 5500 5.1 $200
Sound Card: Sound Blaster Audigy Z2S $60
Keyboard: Logitech LX700 $60
Case: Antec $60
Total: $1644
Balls to Walls:
Motherboard: DFI SLi-DR $180
CPU: AMD X2 4800+ $800
RAM: Crucial Ballistix TCCD CAS 2 2X1GB $280
Graphics Card: 2XeVGA 7800GTX $1000
PSU: PC Powercooling 600 Watt Turbo $230
Hard Drive: 2XWD Raptor 76GB RAID 0 + 500GB Seagate $550
Burner: Plextor 740A $140
Speakers: Logitech 5500 $200
Sound Card: Creative X-Fi $130
Keyboard: Logitech Gaming Mouse and Keyboard $120
Case: Antec P180 $120
Total: $3750
For the monitor, get whatever you want. Preferably at least 19" LCD with a response time of 16ms or faster. As for the hard drive, thats really up to you.
For the low range, I choose the Chaintech and Venice because they are both good and overclock well if you want too. Also the new Venice Rev. E supports faster memory speed the DDR400 with a BIOS flash. As for the graphics card, the 6600gt is the best bang for the buck right now and eVGa because they offer lifetime warranty, as does BFG. For the speakers, I have them and you can't beat it for the price. Really good setup for 40 bucks. The NEC burner is also the best burner for the price also.
As the mid price range, some may think why the fuck an Opteron? Well because these have been getting crazy overclocks with stock voltage and cooling, like 2.7ghz. They are dual-core and also have 1MB of cache each. They only cost 300 as compared to the lowest dual core X2 3800+ which cost $20 more, but has only 512kb of cache. The X2 does perform a tad bit faster than the Opteron, but do not overclock as well. Also, they say the Opterons are basically locked FX series and are high quality because they are server/workstation class processors. The graphics card is a no brainer. Best mid range card aviable. Also the DFI board is one bad ass board that can extremely stable and can be modded to an SLi board with a pencil and circuit pen. The Audigy 2 sound cards are being replaced and they are great now for the price. Way better than onboard. The speakers are the shit too.
The balls to the walls need no explaintion. Best parts avaible for the money. Everything is tops.
All in all, you can mix and match whatever from my suggestions. If you are going to game often, you can choose a lesser cpu and a better graphics card because the game will be GPU limited way before CPU limited. And dont skimp on the power supply. If you do, you may live to regret it because they can take out everything including cpu and motherboard. Stick with name brands like Antec, Tagan, Enermax, OCZ, etc.. As for the RAM. Again, you can just run dividers. AMD has on die memory controller so they don't make that much of a difference. Maybe 5% real-world gains.
Anyway, these are just my suggestions. Go out and have fun.
oh yeah. check out these sites for prices and deals.
www.monarchcomputers.com
www.zipzoomfly.com
www.newegg.com
www.pricegrabber.com
www.froggle.com
www.ewiz.com