Choose between spending money on training old employees or introducing crucial systems and processes for growth and restructuring of a company.

Choosing only one, I'd choose training old employees. Old employees know the business, know the shortcuts but may lack in a particular area or skill (IT, Communication etc) if you give them the skills necessary to over come these hurdles they will perform better and your organizational objectives will be achived. 

I think both go hand in hand, because introducing a crucial system and infrastructure may require to change the current infrastructure and processes of the company and that in turn will create a need for the employees to be trained regarding the use of the newer (considering a positive change ofcourse) system or policies/processes. Apart from that, the firm should understand that the systems and processes are strategic moves that it has to cater to, and hence it would be better to train the employees for the newer systems as they are already aware of the organizational morals and other processes which gives them a sense of belonging too.

Both are essential to build any business. Every company succeeds because of its skilled and efficient employees. Getting the right employees who are loyal to your company is a very difficult thing in today's world. You will have to continously train your existing employees to be adept with the latest technologies and skills as per the requirement of the business. Even if you have proper processes in place, the processes can be put into practice only with the right kind of work force. You will have to strike a balance between the two to successfully take your company forward. Both are essential components and you will need to put proper processes for the smooth functioning of your business.

I believe I will go for both, as the old employees have the needed experience and at the same time , maybe I  need to change the system to restructure the company