Easy question for you guys.

I have an old version of the original Neverwinter Nights (v1.11 - bought secondhand because I'm such a cheapskate). I know that there have been updates since then. Which patch do I need to download to fix up any bugs that are in my version? Alternatively, will getting either of the two expansion packs achieve the same result?

Patch download is automatic - just click the Update button on the starter menu and it'll install the latest patch. Both of the expansions also come pre-patched to a certain patch number, but hitting the Update button will always get you the latest, no matter what. There have been patches after HotU already, and they still keep coming, so you need to get the latest via the Update button in any case, even if you have the expansion(s).

Cheers! This really is the best place to come for advice of that sort.