First time buliding a pc, not much experience. So please comment/criticize without inhibitions.  

Purpose: don't play game often, mainly web, movies, download, etc. Need to be QUIET.

I think the video card can be further downgraded, and use the savings for improvements in other components ( like motherboard or harddrive).

CPU: $199
Intel quad core Q6600
2.4Ghz, FSB: 1066MHZ, L1: 128K+128K, L2: 2x4MB

Video Card: $ 65
XFX PVT84JUDD3 GeForce 8600GT 256MB 128-bit SLI
Memory: 1600MHz
Memory Type: GDDR3
DVI: 2
TV-Out: HDTV Out
Max Resolution: 2560 x 1600

Motherboard: $ 105
Intel BOXDP35DPM LGA 775 Intel P35 ATX
1333/1066MHz, PCI Express x16 - 1, PCI Express x1 - 3, PCI Slots - 3

Memory: $85
GG.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM 800

Harddrive: $45
Western Digital Caviar SE WD1600AAJS 160GB 7200 RPM 8MB Cache SATA 3.0Gb/s
Average Seek Time 8.9ms
Average Latency 4.2ms

DVD: $30
SAMSUNG 20X DVD±R SATA
Cache: 2MB
Speed: DVD+R 20X DVD+RW 8X CD-R 48X CD-RW 32X

Case: $99.9
RAIDMAX SMILODON ATX-612WBP Black SECC STEEL ATX Mid Tower
Power supply: 500W

Monitor: $180
HannsG HW-191DPB Black 19" Widescreen LCD
Built in Speakers
Resolution 1440 x 900
Pixel Pitch 0.283mm
Contrast Ratio 700:1
Response time 5ms

memory can be downgraded, to 2 or even 1gb since its mostly movies and web 

video card could be downgraded but i wouldnt recomend it, since for 65 thats pretty good and if you go too low on video cards you loose hdcp, and blue ray and all that jazz. dont think you need a quadcore btw too, id say go with a nice c2d.

monitor.

i recomend the lg 22 inch (it is around 280ish if you look around, around 380 at best buy) but it is one amazing monitor. vivid colors sharp contrast amazing brightness. the best display you will ever view (at 22 inches) they got a 19 inch too, same specs only 19 inches for around 200ish. check it out its the best display i saw at any retailer.

 I agree, even with a e2xxx, you'll have enough power for any normal desktop app and video.  If you want some more juice, go with the e7200 or similar price: ~130, don't bother with 4gb ram, unless you are running linux or windows 64-bit, as you won't get to use it all anyway.  Reducing the processor and ram will still leave enough power for HD vids and light gaming ie.WOW etc.  I always tell people that the single most important component for a computer is the monitor (at least for 90% of the people). Decrease money spent on RAM/CPU, and put it toward a Quality Monitor.

 Can you provide a link to the power supply you intend to buy. The reason being, although it's a stated 500 Watt if its's a generic supply you may be better off choosing a different one. 

You only want one pci express x16 ?

He's not interested in much gaming, so no reason to pay more more a mobo with a second PCI-e.

If I were you, I'd switch to only 2GB of RAM memory.  That should save $30+.  Put that money toward the Hard Drive.  160GB is not enough Hard Drive space imo.  It's only a little more money for a 250GB drive.  Any RAM over 2GB is kinda overkill anyway.

Thank you for all the answers. I already have an external USB 250GB HD, so don't plant to spend too much on HD.

I plan to get a better motherboard, namely, Gigabyte GA-P35-DS3L. Also, plan to downgrade my video card, any cheaper but still very good video card that you recommend, I do plan to watch HD movies though.

Also, I will go with the e8400 instead of quad core, and get 1066 2Gb RAM as suggested.

Most importantly, I want my box to be quiet, so I can sleep beside it without the fan whirring like a Boeing plane. Should I get a cooler? What kind? I have no idea about coolers.

Thanks! 

 Honestly, $65 for a 8600GT is an excellent deal.  Anything cheaper will be much slower.  And $65 is not a lot of omeny for a video card.

And why get 1066 RAM?  Save money and go for 800 and keep the video card.  But if you must save only a few bucks, go for the Radeon 2600Pro.  Perhaps:

http://www.newegg.com/Product/Product.aspx?Item=N82E16814161194 

Your choice, read the reviews and decide.  Keep in mind it will be slower than the 8600GT if you do anything 3D.

To be honest, if you're looking for a convenient, quiet PC, I would give some serious consideration to the new ASUS Eee Box coming out in mid-July.

For web surfing, email, movies, etc. you really can't beat it.

http://hothardware.com/cs2007/forums/t/38793.aspx

 Oh, and by the way, if you are going to go the build route, I just came across an 8600GT for $49.99

 http://www.buy.com/retail/product.asp?sku=204450333&adid=17653&dcaid=17653

8600GT for $50 is excellent.  Keep in mind it's a mail-in-rebate, however.

I would have to disagree with the Asus EEE PC.  That's more for HTCP computers.  It lacks an optical drive, and the Intel Atom is kind of weak compared to any real desktop CPU.