Hi there, alyoob.
I would recommend a Dell XPS M1730. They are unstopable. I am unsure of your price range, but you can rely on an XPS M1730 to get just about anything done. They start from around $2500 if you're lucky, and can get quite pricey. If you are after a desktop replacement, this is what you want. You can pick the specifications on the Dell website to cater for your every need. You could also go for the more portable, practable option of an XPS M1330 or an XPS M1530. These are both quality machines, and easily render your needs as you mentioned. I would suggest an M1530, as it is in between the M1730 and M1330 in terms of price and performance. However, you wouldn't be able to get a 4GB in the XPS M1330, it's simply too much for the smaller laptop. All in all, you'll be looking at either the XPS M1530 or the XPS M1730. They both have what you are after and it's up to you to decide on your price range.
I hope I have been of assistance.