A hint, just in case.
Besides Monolingual (which removes app and system localisations with dictionaries) and XSlimmer (which removes app localisations according to the list in the International PrefPane), you can also remove the localisation of a single application very easily. If you view the Info Window, by hitting Command-Option-I, you'll notice a language panel, with all the localisations avalaible in the app. Select one or many and then click â€“ (minus) to suppress them. You can even move on to another app with the Info Window open.
For just one or two new app which you newly installed this is easier.
(You could also do it by showing the package content of the app and deleteting manualy the .lproj file but this is prone to error).
Dell Mini 9, 16 GB SSD, 16 GB SDHC, 2 GB RAM, Wifi, Bluetooth, 1.3 MPx WebCam, OS X 10.5.5 (Vanilla Kernel)