Power consumption of video cards:
HD 4650 = ~35w - 40w best guess
HD 4670 = 47w (measured)
9600GT = 60w (measured)
HD 4770 = 80w according to ATI and will be released in May
HD 4830 = 85w (measured)
My advice is to buy either the HD4670 if you are an ATI guy or the 9600GT if you are an nVidia guy. If you don't care then the 9600GT as it generally a little faster than the HD 4670.
If you can wait until May, then go for the HD 4770 which is expected to perform better than the HD 4830, and estimated to come within 5% - 10% of a HD 4850 (which consumes 110w) based on the specs; it's always wise to wait for actual reviews with benchmarks.
Those ATI / nVidia recommended minimum PSU is based on the fact they do not know what else is in your PC; everyone's PC is more or less different. So they play it safe and recommend a minimum PSU that should be more than enough for the average consumer. For example, I may have a Q6600 CPU in my Dell Inspiron 530 which has been measured to consume 88w under load, while your Dell Inspiron 530 has an E1200 CPU which consumes an estimated 22w under load based on several power consumption charts I was researching. Since your CPU consumes an estimated 66w less than my PC you can install a much more hungry video card than I can.
Buy the video card first, then save up money for a CPU upgrade later on. The E1200 will likely bottleneck the HD 4770 a little bit, but in the long run you will be ahead of the game as long as you are willing to upgrade the CPU. Based on the CPU that you currently have, you are most likely limited to the older Conroe / Allendale series CPUs which are based on 65nm tech. The newer Wolfdale 45nm CPU are likely to require a BIOS upgrade for the motherboard, if there is one (doubtful). Therefore you are limited to the following series of CPU upgrades:
E1xxx Series - Don't bother with these Allendale based Celeron CPUs, you already have one.
E2xxx Series - A little better than the Celerons because these Allendale CPUs have double the cache (1MB vs 512KB).
E6xxx Series - This is the series to buy because it comes with 2MB / 4MB of internal cache and has a bus speed (a.k.a. FSB) of 1,024MHz rather than 800MHz (Allendale), but you need DDR2 533 RAM (or faster) to take advantage. It is likely you may have DDR2 400 RAM. All this tech jargon means this series of CPU will be faster because it has more of everything.
Q6xxx Series - These are Quad Core CPU and is overkill for your needs.
Since you have a Dell, ignore any advice about overclocking the CPU because you cannot do so with their motherboard. My advice is to upgrade to an E6400 (2MB of cache) or E6420 (4MB of cache) at a the very least when you have the money. However, since these CPUs are no longer in production, the longer you wait the higher the price to purchase those CPU as inventory dwindle. Additionally, most of those CPU will be OEM (Original Equipment Manufacture) which basically means 1) 30 day - 90 day warranty at best and 2) you will need to purchase the heatsink separately. Do not attempt to use your current CPU heatsink since these faster CPU generate more heat.
P.S.: I am a moron? When I went to Dell's website and I couldn't find a button to add the Dell Inspiron 530 to my cart so that I could check out all the option. Does Dell expect people login first before they can add items to the shopping cart?
P.P.S.: You better not reply back with 'Yes' to the first part of my question above.