after download,will launch video, not programs
 

After i download things just fine, it wont seem to open some of them. But it works (choppy) on the video I want to open SIT files , but the stuffit program i downloaded wont work, or the art programs, etc. The virus scanner i downloaded wont open either, so i can't scan it first. Please help.

Use your favourite file manager for that task. Starting programs from LimeWire usually won't be allowed for security reasons.