Don't let it get you down, sailpog. It's better to ask and find out before than after, right?
I dunno what brands are available on your side of the pond. But I do know it is better to try to get a comp made of stock parts instead of a pre-built, period.
If you can't build your own, talk to a computer shop about building you one. Post what parts the shop wants to use, and we'll let you know if it would be worth it, or what to change. Just try to ignore those who scream about you having to have the newest graphics card or RAIDed Raptors and stuff like that. Buy what you can afford and upgrade down the road.