You will notice two different search options now available, one in the left menu one on the right.
Clicking through on the left Search link will bring you to a search page that looks for words, or the name of the person who posted within a date range. This will search the messages in the forum you are currently in. So if you are in the Building Forum it will search the active messages in the Building Forum. If you click through while you are in an archive it will only search the messages in that archive.
The search on the right menu is a Google full-text search of everything on this site and my Guillemot Kayaks site. You can search posts or images based on relevance or date. Google has over 250,000 pages indexed for this search and there is a huge amount of useful information available.
The forum search on the left is probably most useful to find a particular post you remember, where the Google search on the right is probably best for finding general information about a specific topic.
Please try both and let me know what works for you.