Have a look at some of the HD videos at www.vimeo.com if you’re moving this way with your train movies. Impressive!
If you’re going to be doing HD editing on a PC, some of the relatively inexpensive ATI Radeon graphics cards might be a worthwhile upgrade if your PC has a bog-standard Intel on-board chipset. Most cards appear to use DMS-59 connectors, so be sure you get the right adapter cable for your monitor (VGA or DVI).