not a single rom works, what do i have to do

i have downloaded a few roms lately, but some doesn't unarchive, and the others i can't copy to my r4i. the computer says the file is unreadable. can someone help me, because this really is awfull

Probably corrupted download.
Try using a download manager.

where can i find a download manager?

www.flashget.com is a good one.

Try flashget.

If it extracts from the rar file and you cannot copy it to your R4 then the problem is not with the download but rather with your hard drive or your microSD memory, perhaps you have the lock switch set on your microSD card or perhaps your hard drive is close to dieing?

Try reformatting your sd cards (after copying all roms/savs to your comp)