If the machine has been running XP the BIOS SATA setting will likely be set to Compatibility mode since from what I remember, XP does not have native SATA drivers... for a SATA HD running W7 the BIOS SATA setting should be switched to AHCI. Someone pls correct me if I'm wrong.
But that's only hurdle one. When you installed W7 on the latop, Windows installed all the device drivers relevant to the hardware it was running on... namely the laptop... now you are putting it in a completely different machine and it needs to install the drivers for THAT hardware.
What you are doing is migrating your system to new hardware... and both Paragon and Macrium Reflect handle this, though I have only used Paragon for migration myself. They have a tool called the Boot Media Builder, and another called Recovery Media Builder (the latter is newer but both will accomplish the task). These create a bootable USB stick (or CD) with WinPE (Windows portable environment) on it... so it boots into a Windows GUI with Paragon tools available, and allows you to choose the "P2P" (platform to platform") option, which looks at the OS installed on the internal drive, and injects the proper drivers to make it bootable. It takes 2 seconds.
But making the bootable media takes a little longer as it has to download the WAIK (Windows Assessment Installation Kit) file which is 1.3GB, and install that before the boot media can be created. So this has to be done on a working machine. Also, the BMB and RMB tools are only available if you have an acct with Paragon, unless copies are floating around. You might be able to build a Linux version and skip the WinPE download and hassle, in which case you have to use Recovery Media Builder (RMB) as Boot Media Builder (BMB) only creates a WinPE disc, IIRC, while RMB has either option.
Macrium Reflect also performs system migration from their bootable media, but only their paid version (just like Paragon) will create the tool necessary.
There must be a manual way to inject drivers, but I don't know it.