Given your configuration, I am really surprised it takes twenty seconds. My configuration is about even with yours -- 3 GB of RAM, 2 x 2GHz Athlon64 processor, 7200 rpm IDE hard drive.
Streets & Trips goes to fully working map display from a cold start in 7 seconds. I might've been lucky that it was 7 seconds instead of 8 or 9 (maybe the drive arm just happened to be in the right place), but it wasn't anywhere close to 20 seconds. The extra gig of RAM is unlikely to be the deciding factor (also tried on 2 GB machine), nor the dual-core processor (Streets & Trips not super processor-intensive).
Craplets are a term coined by Walt Mossberg a year or two ago to describe the preloaded junk on most PCs. See
http://ptech.allthingsd.com/20070412...junk-programs/ I'm also including stuff that you may have installed yourself, plus invisible stuff like iTunes helper or the Adobe Reader helper. I see even experienced computer users (some with, yes, 20-30 years of experience, just like you), who run with a dozen tray icons. In contrast, I run with two (plus the OS icons). None of them takes up much resources by itself, but added together they could take quite a bite out of your system.
Other than craplets, the other thing that comes to mind is that you could set your on-access virus scanner to exclude the Streets & Trips directory. You can still scan for viruses periodically, but there's not too much to be gained from scanning an already-installed program every time you start it up -- the on-access scanner is mostly to catch programs that you just downloaded.
I am running Windows Server 2008 (basically Vista without the eye candy), so it's got better prefetching than XP. (Yes, Vista should be faster than XP when you strip out the junk, there've been a lot of beneficial changes under the hood.) No change when I run on a Vista machine, and I recall Streets & Trips was pretty snappy when I ran it on XP too.
I wouldn't give the splash screen too much weight, it's more historical than actual. It was probably vital back in 1998 when S&T had to run on 500 MHz Celerons and fit in 256 MB of RAM. These days it's just legacy. For that matter, Photoshop used to be a super-heavyweight application that brought computers to their knees. It's still pretty heavy, but it now starts up quickly enough that the splash screen is probably dispensable.