My general understanding was that Dell's no-frills Vostro line was meant mostly for the business crowd -- which usually translates to a mediocre-to-average spec on the graphics system. The CPU is fast enough, but without a decent 3D-graphic system, you'll miss out on an appreciable amount of eye-candy (best case scenario) or the program outright refusing to launch. In Vista, right click on your wallpaper and select "Personalize", then click "Display Settings". Preferably, it'll mention something about "nVidia GeForce" or "ATI Radeon". There's a good chance any simulator will consider those sufficient. If it says "Intel GMA", all bets are off and YMMV.
My previous notebook was a Toshiba Qosmio with a (single core) Pentium M at 1.82ghz, WinXP, 2gigs of RAM, and a nVidia Go6600 video system with a measly 64megs of graphics RAM. RealFlight 3.5 ran acceptably on it. Framerate was around 20-25fps with over half of the simulator's graphics goodies toggled on. Could things have been smoother? Yes. Was it useable enough to get-in some training on the road? Absolutely. That system was bought in 2004. It's ancient by today's dual-core standards. IOW, any notebook purchased in the last two years will have a CPU that'll run rings around it, but your graphics system still remains in question.
Given the resource-hungry nature of Vista, it might be a good time to max the system to 4gigs. Two 2gig modules total $30-$35 nowadays. Short term, it'll give your 32-bit Vista more useable ram. Long term, the system can utilize all 4 gigs on a 64-bit OS (Win 7)
UPDATE: a quick Googling seems to indicate a Vostro 1000 has an ATI Radeon Xpress 1150. Performance-wise, one of the online leaderboards seems to suggest it's roughly where my old GeForce Go 6600 was. Those benchmark scores are NOT pretty...
BladeCP, T-Rex CDE, RealFlight DS, RealFlight G3.5