I've already selected mobo, cpu and ram (GA-p35 DS3L + E8400 + patrior dual channel ddr2 800 mhtz)

Now 'm looking for a Good and fast Sata hard drive under 100 $

Can you please recommend? (prefer speed over size)

Any of the new Seagate or WD drives. You should be able to pick up a 7200.11 320GB Seagate for less then $100. If you wait and hunt, you might be able to find a 500GB for around the same, though it might be a bit more.

I would go for this one http://www.newegg.com/Product/Prod [...] 6822148288 . Big, fast and 5 year warranty.

what's the ".10" portion in speed?

most I see online is ".11" is 11 faster than 10?

Here ya go.
Pick any one of these:

http://www.newegg.com/Product/Prod [...] &name=16MB

split between WD6400AAKS and ST3250410AS

The link smartel gave is the absolute BEST HD for this price range available

I agree with smartel, in fact I ordered that exact drive yesterday for a similar system to yours. The price is also down $5 from what its been the past month or two.

The .10 and .11 are the generation of technology used. For example, 7200.10 is the 10th generation of technology they've released on their 7200rpm drives. 7200.11 is their latest and greatest.

2 votes for WD6400AAKS. 2 platters drive with low temp and quick avg write/read for 100bucks

also the WD 640Gb best the seagate ST3500320AS in every aspect(Sizes, temp, average read/write) and only 5 bucks more.

jivdis1x, where are you finding the average read/write times for the WD6400AAKS? I can't find it on their website.
http://www.wdc.com/en/products/pro [...] =en#jump11

Here is data for the Seagate ST3500320AS drive:
Average latency 4.16 msec
Random read seek time <8.5 msec
Random write seek time <9.5 msec
http://www.seagate.com/ww/v/index. [...] Page=Model

I couldn't find exact temperature data for the WD6400AAKS, but Tom's hard drive charts show the 750GB version of that drive (WD7500AAKS) hitting 48 degrees, while the Seagate ST3500320AS tops out at 42. In fact, the Seagate ST3500320AS beats the WD7500AAKS in 12 out of the 15 performance categories. I really wish they would add the WD6400AAKS to the charts.
http://www.tomshardware.com/charts [...] 784%2C1847

If you look at the data sheet, you'll see the Seagate has 2 platters just like the WD. Also, the Seagate comes with double the cache, and 2 more years on the warranty.
http://www.seagate.com/docs/pdf/da [...] 200_11.pdf

I will concede the point on size. 640GB over 500GB at nearly the same price. Really you can't go wrong with either of these drives.

I didn't realize the 640MB was down to $100. I thought it was closer to $120. (nm, I see the $15 off with free shipping...) Getting this drive would be great also. That or a 7200.11, either or. At this price range however, the 640MB would probably provide the most space.

Go for WD Caviar RE2 500GB
Visit here to see some benchs
http://techreport.com/articles.x/10516
http://techreport.com/articles.x/8784

I just got a samsung spinpoint F1 750Gb