Cookies don't take up much space and are accessed by specific web sites that
caused them to be deposited to your hard drive.
Some cookies enable commercial interests to track where you go on the web
for marketing purposes. Try Adwatch, software to block bothersome tracking
and other non-virus events. E.g., cookies called fastclick or tracking
something or other. No harm to delete.
Other cookies keep track of your user ID and password at particular sites,
and similar useful info. You can delete but then you'll have to reenter
said data.
I'd say get Ad-Watch, clean out all your cookies, install Ad-Watch, then
relax.
Richard