I've opened a rar archive using Winace. Whenever I try to extract it, almost every file is said to be corrupt. Do I need to download it again?

No, in most cases the files will be perfectly fine. This problem is caused by the way older versions of Winace handle rar archives. You can avoid these false error reports by using Winrar instead, a trial version of which can be downloaded from www.rarlabs.com.

This is arguably the best compression/extraction program available in any case, so it would be beneficial to have it installed on your system. One of its most useful features is its ability to handle multiple file extractions, yet it has a plethora of other invaluable tools too.

In future, make sure you use Winace for extracting ace archives and Winrar for extracting rar archives if you encounter problems.