Samsung F3 Loses Performance :(

[BigRazer93]

Hello, yestaday I did an crystaldisk Benchmark on my new samsung f3 500gb hard drive. i was getting 140.7mb read and 140.3mb write. Now since i've installed windows 7, anti virus msn and a few games, I'm gettin around 108mb read and write? I've done a defrag on it and didn't do much really? Just wondering why does it lose performance and any ways I can get it back to near its original 104mb read etc? Thanks
I aint an expert with hard drives, thats why im asking for advice

 

[AbsenceJam]

Computer activity is affecting the benchmark.

 

[BigRazer93]

Thanks for the reply. i've just fixed the problem. I did an windows defrag and it said its done. I've got 2 hard drives now so I went into windows xp on my other hd, used tune up utilitys and says the sammy needs to defrag. So i did a benchie and getting 132mb read now Windows defrag etc is a load of **** imho lol