I think I dun goofed, Windows will not boot, but hard drive is fine

UPDATE4: Two people over at r/24hoursupport are agreeing that it's likely not a corrupt MBR issue. Did a drag-and-drop copy of everything in Ubuntu and can verify that my data is safe. Will let SpinRite loose in the morning and see what it can do and at the very least tell me if the drive's in serious shit.

Lately, my computer, famous for bluescreening all the time in my residence, is not booting. This started happening after I was entering my Windows password and it froze. I reset it, then Windows shows the bootloader loading (the what-should-be instantaneous sequence before it gives you a graphical anything) and then suddenly restarts.

I have not installed this month's updates per Woody Leonhard's advice, so it's unlikely that an update zapped me. I did have it set to notify but don't download though.

Here's the specs:

• 32-bit Windows XP (SP3)

• 2 GB dual-channel DDR2 RAM

• BIOSTAR Group N61PB-M2S mobo

• AMD Athlon 64 X2 4200+ CPU at 2.21 GHz

• 128MB GeForce 6150SE nForce 430 (integrated graphics)

• 250 GB Seagate HD

I currently have access and am typing from an Ubuntu USB stick with YUMI. I'm still able to see files no problem, and Ubuntu reports the SMART status says the disk is healthy in Disk Utility. If a screenshot is needed, I'll provide one.

I'm figuring something in the MBR might've gone corrupt. Should I just bail out, clone, get Win7 and a new graphics card and get this over with?