No that was the highend stuff that was out back then, and now its mostly midrange, happens all the time with computers. Personaly I always like buying midrange systems, $700 or so system and its within the same performance class as a $2000+ rig especially if your overclocking, few years down the line you do it all over again.
Don't think your Vista Ultimate has 64bit since its OEM, retail versions of Vista even the lower end ones have 32 and 64bit.
I wouldn't upgrade unless you feel you need the performance, what is the situation that makes you think you need a 2nd GPU? Unless your using 1900x1200 or higher with AA probably won't make much difference.
Another 2gigs of memory would help you alot with Vista though, even though some of it wouldn't be used due to 32bit, 2gigs tends to feel a bit sluggish with Vista and gaming, though its perfecly fine on XP. Its also very cheap 2gig kits these days can be as low as $30 for CAS4 after rebates.