I find it difficult to come up with the perfect work bag solution, especially when you need to carry a laptop around. I thought I had solved the problem when I invested in a Mabel Holdall which could work as a regular handbag and still fit a 14.5" lap top. It turned out not to be that great. The bag was too heavy when carrying a laptop inside and too big for being a handbag (things tend to disappear in the bag). Therefore, at least until the perfect bag has been invented, I think the best solution is a small handbag and a computer bag. Right now there are some really nice computer bags/briefcases around. My two favourites are the ones from Coccinelle, feminine and stylish. 
Top row: Coccinelle Croc Print Leather Work Bag in Anthracite 38x29x8,5 and Coccinelle Saffiano Print Leather Work Bag in Iris 37x27x13 (for resellers check www.coccinelle.com). Second row: Mulberry Heathcliffe briefcase in black 8also available in Oak and Chocolate) 40x31x8,5 (www.mulberry.com) and Louis Vuitton Igor briefcase in gray 36x30x8 (www.louisvuitton.com)
Top row: Coccinelle Croc Print Leather Work Bag in Anthracite 38x29x8,5 and Coccinelle Saffiano Print Leather Work Bag in Iris 37x27x13 (for resellers check www.coccinelle.com). Second row: Mulberry Heathcliffe briefcase in black 8also available in Oak and Chocolate) 40x31x8,5 (www.mulberry.com) and Louis Vuitton Igor briefcase in gray 36x30x8 (www.louisvuitton.com)