I have done mod_rewrites in the past without (AFAIK) any penalty
Code:
RewriteRule ^/links/old-category1.html$ /links/new-category.html [R=301,L]
RewriteRule ^/links/old-category2.html$ /links/new-category.html [R=301,L]
Tells the spiders that the pages have been moved and can be found at the new location from now on.
Another option is a 'hidden' redirect like
Code:
RewriteRule ^/links/old-category1.html$ /links/new-category.html [L]
RewriteRule ^/links/old-category2.html$ /links/new-category.html [L]
The new page is displayed, but the address does not change in the browser, so looks like old page is still being maintained. Yes the content is the same, but it is only one or two pages, so not as if whole site is being copied. As there are no internal links to the old pages, they will gradually lose PR in favour of the new pages.