Worth buying a low range GPU for time being?

lukey2k10

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Jun 14, 2011
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As you're reading this thread,you'll be able to see how new i am to this which i am.
I didn't get my budget right and I seem to have gone around £100 over budget, so instead of getting a hd7870, I can only afford maybe £70. Is it worth buying a £70 graphics card until I can afford £180 or just keep the £70 and continue saving?