I'm not exactly sure what you are asking. The 5450 is a very weak card. The Nvidia equivilant would be the Geforce 6800, 7300GT GDDR3, and 7600GS. If you give us a budget, resolution, and what it will be used for, we will be better able to help you.
It is more of a multimedia card than a gaming card. Yes, you can play games with it but it is very weak.
Without knowing anything else about your PC, I recommend buying the HD 4670 for $55 after rebate + $5 shipping. It is equivalent to the HD 5570 which is still considered to be a multimedia card by today's standards. The HD 4670 was considered a very good mainstream gaming card when it first came out.
The cheapest HD 5450 is $35 + 6 shipping at Newegg.com. However, if gaming is important to you then I would suggest saving up more money for one of the I cards I suggested (the HD 5670 is the best bang for the buck). Otherwise, you will most likely regret your decision and will end up spending more money on a video card soon after you buy the HD 5450.