As for the parts going down, prices are always going down, it's just when you need the stuff. I'm sure if you waited till the summer, you might be able to get the stuff for cheaper, but how much is question. I'm guess prices might drop $80CAD for the over all price, but nothing too much in the next little while. The only huge drop I expect to see in the next few months if from the GF4, which will drop prices of the GF3 by alot, but then again I said that about my Radeon 64mb DDR, which still cost like $250CAD (I paid $300CAD w tax about 4 months ago!) And my processor has only gone down like $20 and for the mother board! Though the ram prices went up from when I bought my stuff! I really got a good deal with what I was going for, but I still have alot of left over's from my old system (Like my 19" monitor.)
If the money is tight, wait. If not and you already have the money saved up to spend, it's a trade off. Time with the Computer listed Versus saving X amount of money for each component. If you really don't need it yet, wait a bit. If you wanted it now, well it's all up to you