I would like some advice in this matter, because I can't really come to a decision and the local forums are not as active in this matter, so I hope that the mac enthusiasts over here can help me 
First I would like to state that money is not the most important lever (that's why the choice could be the basis 13" or top-end 17"). I just (5mo ago) bought a Dell Studio XPS 16 high-end (16" HD RGB LED, SSD, 512MB mobile card) as a replacement of my ex-MBP 15" 2007 model, this was, after time, a wrong decision and is going to cost me a lot more money than making now a right decision between a 13" or 17" model.
I use the laptop for work and recreatively, it's my main instrument, so it's very important that it doesn't annoy me or it leaves as quicky as my current Dell
I also just bought a ACD LED 24" display (current without purpose because I need a displayport
), the MBP in this matter will be connected to this screen for professional use.
Besides recreational use (surfing, viewing HD content, ...) the laptop will also be used for architectural purposes (plan editing), photo editing and I also would like to start with 3D rendering of building and interiors.
I'm also thinking of replacing the HDD after purchase with an aftermarket SSD Intel X25-M 160GB and if needed (in case of MBP 13" basic model) a 4GB or 6GB RAM upgrade.
As stated before, if it's not needed to spend 2500 I'm not going to (the SSD is already a 380 upgrade) so I hope that a realistic advice is possible rather than if you have the money go for the 17" model
Thanks in advance for the greatly appreciated advice and sorry if grammatical mistakes were made as it's not my native language
First I would like to state that money is not the most important lever (that's why the choice could be the basis 13" or top-end 17"). I just (5mo ago) bought a Dell Studio XPS 16 high-end (16" HD RGB LED, SSD, 512MB mobile card) as a replacement of my ex-MBP 15" 2007 model, this was, after time, a wrong decision and is going to cost me a lot more money than making now a right decision between a 13" or 17" model.
I use the laptop for work and recreatively, it's my main instrument, so it's very important that it doesn't annoy me or it leaves as quicky as my current Dell
I also just bought a ACD LED 24" display (current without purpose because I need a displayport
Besides recreational use (surfing, viewing HD content, ...) the laptop will also be used for architectural purposes (plan editing), photo editing and I also would like to start with 3D rendering of building and interiors.
I'm also thinking of replacing the HDD after purchase with an aftermarket SSD Intel X25-M 160GB and if needed (in case of MBP 13" basic model) a 4GB or 6GB RAM upgrade.
As stated before, if it's not needed to spend 2500 I'm not going to (the SSD is already a 380 upgrade) so I hope that a realistic advice is possible rather than if you have the money go for the 17" model
Thanks in advance for the greatly appreciated advice and sorry if grammatical mistakes were made as it's not my native language