Saying you majored in "computer engineering" (CompE) is a bit vague. Within the USA, each university/campus has its own definition of CompE. At some universities, it's a merge of electrical-engineering (EE) and computer-science. At others, it's a specialization/branch of EE, with a heavy emphasis on computer (processor) applications. Might I ask which university you attended?
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The high-tech industry as a whole has brutal business cycles, which can translate into high job-turnover regardless of your work performance. Therefore, in my opinion, you should focus your electives on courses which give you the best overall career prospects.
You need to juggle the your own personal interests, your personal talents (what you're good at), and the market requirements (what skills are in demand.) If you're lucky, maybe for you all 3 match perfectly, otherwise you'll have to make compromise decisions. Unfortunately, 2 of these 3 (your interests and the market) change over time. The market especially changes rapidly and without warning.
Pursuing PC-graphics is a noble goal. But as an industry, PC graphics *HARDWARE* has already experienced a big shakeout (consolidation into a few remaining major players), which means the job-distribution is fairly tight. Basically, the entire market is controlled by a handful of uber-elite engineers (clustered in a handful of companies.) There is little or no 'second tier' (i.e. the rest of the average folks), not any with a significant market (and employment) presence. The software side is probably better. Aside from the hardware companies, you at least have the multimedia companies. But I have no clue whether it's melatively harder to break into the 3D-software job versus a 3D-hardware job. It could be just as difficult.
To answer the qeustion at hand, today's GPUs are every bit as complex and diverse (in terms of the involved design disciplines) as CPUs. Translated into personnel/staffing requirements, that means any LSI/digital/architecture/programming coursework you take will find some kind of employment within graphics company. 3dcgi already listed some the basic skills. All I can add is ...
Front-end design: Being able to do digital-logic design (turn state-machine diagrams into working gate-circuits) is a critical skill, but as the EE-industry moves forward, the Verilog-coder has become a commodity. If you're good at math and statistics, take some DSP and wireless communications classes. If you like pinging other people, take some network protocol and architecture classes. If you like watching Quake timedemos over and over, take some computer graphics classes. The idea is to get some theory in 1+ application-area *besides* just digital-logic-design.
Despite the current downturn in the communications segment, the wireless/comm market is likely to grown into the largest (and most diverse) segment that your career can access.
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