Yea, I agree with raingrove =)
Please don't ask him to buy higher end lenses when he's just started out photography..
I too started with a 450D, 18-55 kit and 50F1.8.. Used it for about 1yr, learning along the way. When light wasn't enough, I would use the 50mm stopped down to abt 2.8..
Soon, you would (probably la..) realse the limitations of your lenses, and then you can really know wat you want to buy.. Like the next lens I got was the EFS55-250, realised that kit lens 55mm not enough reach, esp at zoo/bird park, etc..
Using the 18-55, 50, 55-250, I was pretty contented with shots I got.. Although indoors, when there's low light, the 18-55 wasnt fast enough, and the 50mm not wide enough, that's when I decided to buy a canon 17-55 and a 430EXII.. Never looked back from then.. Love the 17-55!!
I've since got a couple more other stuff, but the main point is that I dont think you should spend the $$ (i assumed hard earned/saved), until you know what you want.. And when that time comes, you could consider 2nd hand to save $$ too..
Good luck and enjoy shooting!!