Beginning to not believe the 1GB Kingston Japan thing, of which I have two. Don't play either of those games myself either so may just go with the kingston 2GB for £12.90 from www.picstop.co.uk.
Also got a cyclo ds and the 4GB sandisk is down to £39 already, that's dropped by 20% in about a month! Prices are just tumbling with memory.
I got a kingston 2gb from buy.com. It's taiwanese (not japanese, if that matters). Haven't tried any tony hawk or castlevania games yet, though. Too busy trying out others yet. Haven't had any problems, and don't think I will.
I have a Kingston 2GB and it's Taiwan (I'm pretty sure all 2GB are Taiwan.) It works fine, but I haven't tested it with Tony Hawk (Why would I want to play those on the DS?) and Castlevania: PoR (I own it, and you should to!)
I used to sell 2gb kingstons, all Taiwan made, and had 1 or 2 complaints referring to Castlevania.
Switched to Integral 2gb Japan made SD-C02G cards, never had a complaint since.