Vista home premium 32 bit upgrade

well...the reason i asked, is that i have vista 32 bit , just bought an oem version....i installed it on a laptop that had 64bit..i bought a 2.5 inch encloser to put the extra hard drive in with the 64 bit...but my 32 bit laptop vista will not boot from it..i don,t get it..it should came off the same computer.
 

yes, its listed in the boot devices.....i just found some things out...you cannot boot from external drive with windows 7...microsoft will not support it...i am thinking its the reason why i cannot boot from vista on my 2.5 inch incloser...microshaft just does not support such booting..i have a thumb drive i cannot boot from either with microshaft...so i believe its not supported