A dedicated card will always outperform an integrated chip, especially if said integrated chip was made by Intel. For fluid play at highest settings, dedicated cards are a must-have.
Do not, repeat, do not understimate Intel IGPs, right now the Intel Iris Pro 5200 is the best integrate video for notebooks, so much it can outperform desktop based A10-5800 and 6800K.
http://www.anandtech.com/show/6993/intel-iris-pro-5200-graphics-review-core-i74950hq-testedIntel really improved their IGP starting from Sandy Bridge, the Intel HD3000 overcloked can outperform a GT520/610 overcloked
This is a test a did myselft

The HD4600 is a way improved version of the Ivy Bridge HD4000, ive seem playing Battlefield 3 720P on medium at +30fps
Off course if you live in EEUU you can buy a better video card for next to nothing, but its not the same if a HD7770 equals a month of minimum salary pay on your country.
On FS2 i did have loots of problems with the HD3000, right now it just crash with malloc errors, its probably because i do not assign it more than 32mb of fixed memory, because no program ever uses it, the driver just send everything to DVT memory, and fixed memory stays at 16mb of use, so if i assign, say 512 or 1gb is just wasted ram.