Help needed-CAD 2d work

hi, need pc which runs flight simulator x & rendering work using autocad & photoshop, predominately used for 2d work...with a wee bit of usage using 3d.
have read tons regarding using a workstation graphics card vs a high end gaming card???
i think im going crazyyyyyy
can someone pls clarify which card is best for my situation ?

what performance would i get from cad using a gtx 260 ( as that card is within my budget)

also i read that the gtx 260 cant be soft modded? is it best to go for a high end card, or a older 9800gtx, or 8800gtc & soft mod? ideally i dont want to soft mod IF the higher end performs well in cad 2d applications

kind regards