seemless security in windows vista which is making tough to manage my laptop
 

I have gone through windows xp for 6 years and only thing we find disadvantage is security because windows xp is well known easily virus can be made for windows systems and hackers can easily gain access.
Windows vista is secured but it is not in a stable state at present. One thing i hate is the user permissions.When i bought the laptop from Dell, it is preloaded with windows vista Basic edition and got only 2 partitions C;D;.one for OS and all relative files are dumped into this drive and another is used as recovery Disc. When i tried to download some thing into one of the folders of C; drive, it is leaving warning message that you don't have permissions to make changes to this folder.So, i have to make changes to the folder file permissions every time.
When i want to format my USB drive from administrator which i created after my laptop is delievered, It is displaying a warning that i don't have permissions to that. It is the only administrator on my system.
What is the problem? what i have to do to gain full permissions?