The Medion PC is absolutely fine for what you'll be using it for. The graphics (GT210) is a bit weak for games, but might be OK for FM2010. Would be best to enquire at their forums click here.
Of the PCs listed, the one with the 'best' graphics (though only slightly better than the GT210) is the Matrix Pro 925 Nero with its HD5450. Don't buy a PC with integrated/HD3200 graphics, unless you plan to upgrade with a suitable dedicated graphics card. Try not to go lower than a HD4670 click here (£47 at time of posting).
DDR3 RAM is better than DDR2, but for your use, next to no difference.
22" monitors at eBuyer click here. It may be best to get a 1920x1080 'Full HD' resolution monitor for films, although a 1680x1050 may suit FM2010 better? Perhaps another thing to enquire about at the FM2010 forum. G