So, during a conversation at PyCon UK, Keith White noticed that he owned the same model (HP nx6325) laptop as me. He also informed me that his processor was 64-bit, and asserted that mine probably was as well.
I was sceptical. It's a Mobile Sempron - last I checked, all Semprons were 32-bit. Of course, I don't keep up with hardware at all. Checking /proc/cpuinfo:
tim@regulus:~$ cat /proc/cpuinfo <br /> processor : 0<br /> vendor_id : AuthenticAMD<br /> cpu family : 15<br /> model : 76<br /> model name : Mobile AMD Sempron(tm) Processor 3500+<br /> stepping : 2<br /> cpu MHz : 800.000<br /> cache size : 512 KB<br /> fdiv_bug : no<br /> hlt_bug : no<br /> f00f_bug : no<br /> coma_bug : no<br /> fpu : yes<br /> fpu_exception : yes<br /> cpuid level : 1<br /> wp : yes<br /> flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow up pni cx16 lahf_lm extapic cr8_legacy ts fid vid ttp tm stc<br /> bogomips : 1597.70<br /> clflush size : 64
The 'lm' flag means 64-bit. So intuitive and obvious... so I guess that's one more thing to try when I get around to reinstalling my laptop.