I looked at the HP M9600t at that priced out at $1309 but like the fact that it had a Acsis mother board but I don't need all there silly drive bays and it appears it has 6 slots for memory and tops out at 12 gigs which in reality is fine.
I then found the dell XPS and priced out a similar system $1189 a little cheaper. It looks like that will top out at 24 gigs but I can't find any other specs on the board like FSB speed etc. Also there case is not that great at cooling from what I read.
The last option is I can build one I am not usally a fan of building but I have in the past. When I price something out to build it is not really any cheaper and I alwas have some issue, at least if I buy one I can alwas send it back or make a call.
I am going to use this mainly for web devlopnment, Pics, editing movies, and email and some coding. Going with Vista Ultimate. I am specing a semi basc video card something with 256 or 512 megs and on board sound. If I am making a mistake let me know.
Ideally here you'll always get people that will tell you option 3 is the way to go and for many valid reasons.
Is it possible you could give us a quick rundown one what parts you have and wouldn't be needing to buy.
I'm also curious to know what the stats are on the system your looking to replace. I'm not sure with what you've noted above warrents a computer as expensive as your looking for it seems. That's why i'm asking to get an idea of what your expectations are for this new build to be like.