I run both sims 4 and 3 on this old laptop..Dell Latitude E650p. Must be dirt cheap even in Ireland (from New Zealand). Its only and Intel Core 2 Duo 64bit, CPUP8600 @2.40ghz, 4gb ram NVIDIA QUADRO NVS 160M...strange but I have all S3 games loaded, I load lots of content (I always defrag, and delete the DCbackup folder each time I install content and install only 100 to 200 items at a time but have had up to 20,000 items in total). My C drive only has 232gb. How's That!? I have a Dell XPS I7-2730qm CPU @ 2.00ghz, 8gb ram also 64bit that crashes each time I try to play (could be that it overheats it could be that it has not enough ghz).
So try to go with an I7, with at least 2.40ghz, minimum 4gb ram...250-500gb internal memory. Write it down, Harvey Normans is fairly expensive, other online shops may be more useful if you email them and explain. Or you could just get a refurbished 2nd hand, cheap Dell Latitude E650 with the same specs at least as mine. If it works for me should work for you.