I've fixed about 90% of the broken links. There are still a lot of pages with the old ".html" suffix instead of ".shtml" that I need to find and fix. There's also some images and cross-page links that are broken.

(For the curious, I'm using Xenu's Link Sleuth.)

Statistics for managers
Correct internal URLs, by MIME type:
text/html 1006 URLs 8676849 Bytes (8473 KB) 69.72%
text/xml 1 URLs 12692 Bytes (12 KB) 0.07%
text/css 1 URLs 1850 Bytes (1 KB) 0.07%
image/jpeg 407 URLs 42939203 Bytes (41932 KB) 28.21%
image/gif 22 URLs 387046 Bytes (377 KB) 1.52%
text/plain 6 URLs 25242 Bytes (24 KB) 0.42%
Total 1443 URLs 52042882 Bytes (50823 KB) 100.00%
All pages, by result type:
ok 1443 URLs 45.51%
skip external 1455 URLs 45.88%
not found 272 URLs 8.58%
connection aborted 1 URLs 0.03%